Uplink Signal Starting Position in a Wireless Device and Wireless Network

ABSTRACT

A wireless device may receive one or more messages comprising configuration parameters of a licensed assisted access (LAA) cell. The wireless device may receive downlink control information (DCI) for the LAA cell. The DCI may comprise a first field and a second field. The first field may indicate uplink resources for an uplink subframe of the LAA cell. The second field may indicate a first starting position in a plurality of starting positions in the uplink subframe. The first starting position in the uplink subframe may be determined, at least, based on a sum of a listen-before-talk (LBT) period and a timing advance value. The wireless device may generate one or more transport blocks employing the DCI. The wireless device may transmit the one or more transport blocks in the uplink resources starting from the starting position of the uplink subframe.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/589,411, filed May 8, 2017, which claims the benefit of U.S.Provisional Application No. 62/332,510, filed May 6, 2016, each of whichis hereby incorporated by reference in its entirety.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Examples of several of the various embodiments of the present disclosureare described herein with reference to the drawings.

FIG. 1 is a diagram depicting example sets of OFDM subcarriers as per anaspect of an embodiment of the present disclosure.

FIG. 2 is a diagram depicting an example transmission time and receptiontime for two carriers in a carrier group as per an aspect of anembodiment of the present disclosure.

FIG. 3 is an example diagram depicting OFDM radio resources as per anaspect of an embodiment of the present disclosure.

FIG. 4 is an example block diagram of a base station and a wirelessdevice as per an aspect of an embodiment of the present disclosure.

FIG. 5A, FIG. 5B, FIG. 5C and FIG. 5D are example diagrams for uplinkand downlink signal transmission as per an aspect of an embodiment ofthe present disclosure.

FIG. 6 is an example diagram for a protocol structure with CA and DC asper an aspect of an embodiment of the present disclosure.

FIG. 7 is an example diagram for a protocol structure with CA and DC asper an aspect of an embodiment of the present disclosure.

FIG. 8 shows example TAG configurations as per an aspect of anembodiment of the present disclosure.

FIG. 9 is an example message flow in a random access process in asecondary TAG as per an aspect of an embodiment of the presentdisclosure.

FIG. 10 is an example diagram depicting a downlink burst as per anaspect of an embodiment of the present disclosure.

FIG. 11 is an example diagram depicting a plurality of cells as per anaspect of an embodiment of the present disclosure.

FIG. 12 is an example diagram depicting a plurality of cells as per anaspect of an embodiment of the present disclosure.

FIG. 13 is an example diagram depicting a plurality of cells as per anaspect of an embodiment of the present disclosure.

FIG. 14 is an example diagram depicting a plurality of cells as per anaspect of an embodiment of the present disclosure.

FIG. 15 is an example diagram depicting a plurality of cells as per anaspect of an embodiment of the present disclosure.

FIG. 16 is an example diagram depicting a timing advance as per anaspect of an embodiment of the present disclosure.

FIG. 17 is an example diagram depicting downlink and uplink subframetiming as per an aspect of an embodiment of the present disclosure.

FIG. 18 is an example diagram depicting downlink and uplink subframetiming as per an aspect of an embodiment of the present disclosure.

FIG. 19 is an example diagram depicting a subframe configuration as peran aspect of an embodiment of the present disclosure.

FIG. 20 is an example flow diagram as per an aspect of an embodiment ofthe present disclosure.

DETAILED DESCRIPTION OF EMBODIMENTS

Example embodiments of the present disclosure enable operation ofcarrier aggregation. Embodiments of the technology disclosed herein maybe employed in the technical field of multicarrier communicationsystems.

The following Acronyms are used throughout the present disclosure:

ASIC application-specific integrated circuit

BPSK binary phase shift keying

CA carrier aggregation

CSI channel state information

CDMA code division multiple access

CSS common search space

CPLD complex programmable logic devices

CC component carrier

DL downlink

DCI downlink control information

DC dual connectivity

EPC evolved packet core

E-UTRAN evolved-universal terrestrial radio access network

FPGA field programmable gate arrays

FDD frequency division multiplexing

HDL hardware description languages

HARQ hybrid automatic repeat request

IE information element

LAA licensed assisted access

LTE long term evolution

MCG master cell group

MeNB master evolved node B

MIB master information block

MAC media access control

MAC media access control

MME mobility management entity

NAS non-access stratum

OFDM orthogonal frequency division multiplexing

PDCP packet data convergence protocol

PDU packet data unit

PHY physical

PDCCH physical downlink control channel

PHICH physical HARQ indicator channel

PUCCH physical uplink control channel

PUSCH physical uplink shared channel

PCell primary cell

PCell primary cell

PCC primary component carrier

PSCell primary secondary cell

pTAG primary timing advance group

QAM quadrature amplitude modulation

QPSK quadrature phase shift keying

RBG Resource Block Groups

RLC radio link control

RRC radio resource control

RA random access

RB resource blocks

SCC secondary component carrier

SCell secondary cell

Scell secondary cells

SCG secondary cell group

SeNB secondary evolved node B

sTAGs secondary timing advance group

SDU service data unit

S-GW serving gateway

SRB signaling radio bearer

SC-OFDM single carrier-OFDM

SFN system frame number

SIB system information block

TAI tracking area identifier

TAT time alignment timer

TDD time division duplexing

TDMA time division multiple access

TA timing advance

TAG timing advance group

TB transport block

UL uplink

UE user equipment

VHDL VHSIC hardware description language

Example embodiments of the disclosure may be implemented using variousphysical layer modulation and transmission mechanisms. Exampletransmission mechanisms may include, but are not limited to: CDMA, OFDM,TDMA, Wavelet technologies, and/or the like. Hybrid transmissionmechanisms such as TDMA/CDMA, and OFDM/CDMA may also be employed.Various modulation schemes may be applied for signal transmission in thephysical layer. Examples of modulation schemes include, but are notlimited to: phase, amplitude, code, a combination of these, and/or thelike. An example radio transmission method may implement QAM using BPSK,QPSK, 16-QAM, 64-QAM, 256-QAM, and/or the like. Physical radiotransmission may be enhanced by dynamically or semi-dynamically changingthe modulation and coding scheme depending on transmission requirementsand radio conditions.

FIG. 1 is a diagram depicting example sets of OFDM subcarriers as per anaspect of an embodiment of the present disclosure. As illustrated inthis example, arrow(s) in the diagram may depict a subcarrier in amulticarrier OFDM system. The OFDM system may use technology such asOFDM technology, DFTS-OFDM, SC-OFDM technology, or the like. Forexample, arrow 101 shows a subcarrier transmitting information symbols.FIG. 1 is for illustration purposes, and a typical multicarrier OFDMsystem may include more subcarriers in a carrier. For example, thenumber of subcarriers in a carrier may be in the range of 10 to 10,000subcarriers. FIG. 1 shows two guard bands 106 and 107 in a transmissionband. As illustrated in FIG. 1, guard band 106 is between subcarriers103 and subcarriers 104. The example set of subcarriers A 102 includessubcarriers 103 and subcarriers 104. FIG. 1 also illustrates an exampleset of subcarriers B 105. As illustrated, there is no guard band betweenany two subcarriers in the example set of subcarriers B 105. Carriers ina multicarrier OFDM communication system may be contiguous carriers,non-contiguous carriers, or a combination of both contiguous andnon-contiguous carriers.

FIG. 2 is a diagram depicting an example transmission time and receptiontime for two carriers as per an aspect of an embodiment of the presentdisclosure. A multicarrier OFDM communication system may include one ormore carriers, for example, ranging from 1 to 10 carriers. Carrier A 204and carrier B 205 may have the same or different timing structures.Although FIG. 2 shows two synchronized carriers, carrier A 204 andcarrier B 205 may or may not be synchronized with each other. Differentradio frame structures may be supported for FDD and TDD duplexmechanisms. FIG. 2 shows an example FDD frame timing. Downlink anduplink transmissions may be organized into radio frames 201. In thisexample, the radio frame duration is 10 msec. Other frame durations, forexample, in the range of 1 to 100 msec may also be supported. In thisexample, each 10 ms radio frame 201 may be divided into ten equallysized subframes 202. Other subframe durations such as 0.5 msec, 1 msec,2 msec, and 5 msec may also be supported. Subframe(s) may consist of twoor more slots (for example, slots 206 and 207). For the example of FDD,10 subframes may be available for downlink transmission and 10 subframesmay be available for uplink transmissions in each 10 ms interval. Uplinkand downlink transmissions may be separated in the frequency domain.Slot(s) may include a plurality of OFDM symbols 203. The number of OFDMsymbols 203 in a slot 206 may depend on the cyclic prefix length andsubcarrier spacing.

FIG. 3 is a diagram depicting OFDM radio resources as per an aspect ofan embodiment of the present disclosure. The resource grid structure intime 304 and frequency 305 is illustrated in FIG. 3. The quantity ofdownlink subcarriers or RBs (in this example 6 to 100 RBs) may depend,at least in part, on the downlink transmission bandwidth 306 configuredin the cell. The smallest radio resource unit may be called a resourceelement (e.g. 301). Resource elements may be grouped into resourceblocks (e.g. 302). Resource blocks may be grouped into larger radioresources called Resource Block Groups (RBG) (e.g. 303). The transmittedsignal in slot 206 may be described by one or several resource grids ofa plurality of subcarriers and a plurality of OFDM symbols. Resourceblocks may be used to describe the mapping of certain physical channelsto resource elements. Other pre-defined groupings of physical resourceelements may be implemented in the system depending on the radiotechnology. For example, 24 subcarriers may be grouped as a radio blockfor a duration of 5 msec. In an illustrative example, a resource blockmay correspond to one slot in the time domain and 180 kHz in thefrequency domain (for 15 KHz subcarrier bandwidth and 12 subcarriers).

FIG. 5A, FIG. 5B, FIG. 5C and FIG. 5D are example diagrams for uplinkand downlink signal transmission as per an aspect of an embodiment ofthe present disclosure. FIG. 5A shows an example uplink physicalchannel. The baseband signal representing the physical uplink sharedchannel may perform the following processes. These functions areillustrated as examples and it is anticipated that other mechanisms maybe implemented in various embodiments. The functions may comprisescrambling, modulation of scrambled bits to generate complex-valuedsymbols, mapping of the complex-valued modulation symbols onto one orseveral transmission layers, transform precoding to generatecomplex-valued symbols, precoding of the complex-valued symbols, mappingof precoded complex-valued symbols to resource elements, generation ofcomplex-valued time-domain DFTS-OFDM/SC-FDMA signal for each antennaport, and/or the like.

Example modulation and up-conversion to the carrier frequency of thecomplex-valued DFTS-OFDM/SC-FDMA baseband signal for each antenna portand/or the complex-valued PRACH baseband signal is shown in FIG. 5B.Filtering may be employed prior to transmission.

An example structure for Downlink Transmissions is shown in FIG. 5C. Thebaseband signal representing a downlink physical channel may perform thefollowing processes. These functions are illustrated as examples and itis anticipated that other mechanisms may be implemented in variousembodiments. The functions include scrambling of coded bits in each ofthe codewords to be transmitted on a physical channel; modulation ofscrambled bits to generate complex-valued modulation symbols; mapping ofthe complex-valued modulation symbols onto one or several transmissionlayers; precoding of the complex-valued modulation symbols on each layerfor transmission on the antenna ports; mapping of complex-valuedmodulation symbols for each antenna port to resource elements;generation of complex-valued time-domain OFDM signal for each antennaport, and/or the like.

Example modulation and up-conversion to the carrier frequency of thecomplex-valued OFDM baseband signal for each antenna port is shown inFIG. 5D. Filtering may be employed prior to transmission.

FIG. 4 is an example block diagram of a base station 401 and a wirelessdevice 406, as per an aspect of an embodiment of the present disclosure.A communication network 400 may include at least one base station 401and at least one wireless device 406. The base station 401 may includeat least one communication interface 402, at least one processor 403,and at least one set of program code instructions 405 stored innon-transitory memory 404 and executable by the at least one processor403. The wireless device 406 may include at least one communicationinterface 407, at least one processor 408, and at least one set ofprogram code instructions 410 stored in non-transitory memory 409 andexecutable by the at least one processor 408. Communication interface402 in base station 401 may be configured to engage in communicationwith communication interface 407 in wireless device 406 via acommunication path that includes at least one wireless link 411.Wireless link 411 may be a bi-directional link. Communication interface407 in wireless device 406 may also be configured to engage in acommunication with communication interface 402 in base station 401. Basestation 401 and wireless device 406 may be configured to send andreceive data over wireless link 411 using multiple frequency carriers.According to aspects of an embodiments, transceiver(s) may be employed.A transceiver is a device that includes both a transmitter and receiver.Transceivers may be employed in devices such as wireless devices, basestations, relay nodes, and/or the like. Example embodiments for radiotechnology implemented in communication interface 402, 407 and wirelesslink 411 are illustrated are FIG. 1, FIG. 2, FIG. 3, FIG. 5, andassociated text.

An interface may be a hardware interface, a firmware interface, asoftware interface, and/or a combination thereof. The hardware interfacemay include connectors, wires, electronic devices such as drivers,amplifiers, and/or the like. A software interface may include codestored in a memory device to implement protocol(s), protocol layers,communication drivers, device drivers, combinations thereof, and/or thelike. A firmware interface may include a combination of embeddedhardware and code stored in and/or in communication with a memory deviceto implement connections, electronic device operations, protocol(s),protocol layers, communication drivers, device drivers, hardwareoperations, combinations thereof, and/or the like.

The term configured may relate to the capacity of a device whether thedevice is in an operational or non-operational state. Configured mayalso refer to specific settings in a device that effect the operationalcharacteristics of the device whether the device is in an operational ornon-operational state. In other words, the hardware, software, firmware,registers, memory values, and/or the like may be “configured” within adevice, whether the device is in an operational or nonoperational state,to provide the device with specific characteristics. Terms such as “acontrol message to cause in a device” may mean that a control messagehas parameters that may be used to configure specific characteristics inthe device, whether the device is in an operational or non-operationalstate.

According to various aspects of an embodiment, an LTE network mayinclude a multitude of base stations, providing a user planePDCP/RLC/MAC/PHY and control plane (RRC) protocol terminations towardsthe wireless device. The base station(s) may be interconnected withother base station(s) (for example, interconnected employing an X2interface). Base stations may also be connected employing, for example,an S1 interface to an EPC. For example, base stations may beinterconnected to the MME employing the S1-MME interface and to the S-G)employing the S1-U interface. The S1 interface may support amany-to-many relation between MMEs/Serving Gateways and base stations. Abase station may include many sectors for example: 1, 2, 3, 4, or 6sectors. A base station may include many cells, for example, rangingfrom 1 to 50 cells or more. A cell may be categorized, for example, as aprimary cell or secondary cell. At RRC connectionestablishment/re-establishment/handover, one serving cell may providethe NAS (non-access stratum) mobility information (e.g. TAI), and at RRCconnection re-establishment/handover, one serving cell may provide thesecurity input. This cell may be referred to as the Primary Cell(PCell). In the downlink, the carrier corresponding to the PCell may bethe Downlink Primary Component Carrier (DL PCC), while in the uplink,the carrier corresponding to the PCell may be the Uplink PrimaryComponent Carrier (UL PCC). Depending on wireless device capabilities,Secondary Cells (SCells) may be configured to form together with thePCell a set of serving cells. In the downlink, the carrier correspondingto an SCell may be a Downlink Secondary Component Carrier (DL SCC),while in the uplink, it may be an Uplink Secondary Component Carrier (ULSCC). An SCell may or may not have an uplink carrier.

A cell, comprising a downlink carrier and optionally an uplink carrier,may be assigned a physical cell ID and a cell index. A carrier (downlinkor uplink) may belong to only one cell. The cell ID or Cell index mayalso identify the downlink carrier or uplink carrier of the cell(depending on the context it is used). In the specification, cell ID maybe equally referred to a carrier ID, and cell index may be referred tocarrier index. In implementation, the physical cell ID or cell index maybe assigned to a cell. A cell ID may be determined using asynchronization signal transmitted on a downlink carrier. A cell indexmay be determined using RRC messages. For example, when thespecification refers to a first physical cell ID for a first downlinkcarrier, the specification may mean the first physical cell ID is for acell comprising the first downlink carrier. The same concept may apply,for example, to carrier activation. When the specification indicatesthat a first carrier is activated, the specification may also mean thatthe cell comprising the first carrier is activated.

Embodiments may be configured to operate as needed. The disclosedmechanism may be performed when certain criteria are met, for example,in a wireless device, a base station, a radio environment, a network, acombination of the above, and/or the like. Example criteria may bebased, at least in part, on for example, traffic load, initial systemset up, packet sizes, traffic characteristics, a combination of theabove, and/or the like. When the one or more criteria are met, variousexample embodiments may be applied. Therefore, it may be possible toimplement example embodiments that selectively implement disclosedprotocols.

A base station may communicate with a mix of wireless devices. Wirelessdevices may support multiple technologies, and/or multiple releases ofthe same technology. Wireless devices may have some specificcapability(ies) depending on its wireless device category and/orcapability(ies). A base station may comprise multiple sectors. When thisdisclosure refers to a base station communicating with a plurality ofwireless devices, this disclosure may refer to a subset of the totalwireless devices in a coverage area. This disclosure may refer to, forexample, a plurality of wireless devices of a given LTE release with agiven capability and in a given sector of the base station. Theplurality of wireless devices in this disclosure may refer to a selectedplurality of wireless devices, and/or a subset of total wireless devicesin a coverage area which perform according to disclosed methods, and/orthe like. There may be a plurality of wireless devices in a coveragearea that may not comply with the disclosed methods, for example,because those wireless devices perform based on older releases of LTEtechnology.

FIG. 6 and FIG. 7 are example diagrams for protocol structure with CAand DC as per an aspect of an embodiment of the present disclosure.E-UTRAN may support Dual Connectivity (DC) operation whereby a multipleRX/TX UE in RRC_CONNECTED may be configured to utilize radio resourcesprovided by two schedulers located in two eNBs connected via a non-idealbackhaul over the X2 interface. eNBs involved in DC for a certain UE mayassume two different roles: an eNB may either act as an MeNB or as anSeNB. In DC a UE may be connected to one MeNB and one SeNB. Mechanismsimplemented in DC may be extended to cover more than two eNBs. FIG. 7illustrates one example structure for the UE side MAC entities when aMaster Cell Group (MCG) and a Secondary Cell Group (SCG) are configured,and it may not restrict implementation. Media Broadcast MulticastService (MBMS) reception is not shown in this figure for simplicity.

In DC, the radio protocol architecture that a particular bearer uses maydepend on how the bearer is setup. Three alternatives may exist, an MCGbearer, an SCG bearer and a split bearer as shown in FIG. 6. RRC may belocated in MeNB and SRBs may be configured as a MCG bearer type and mayuse the radio resources of the MeNB. DC may also be described as havingat least one bearer configured to use radio resources provided by theSeNB. DC may or may not be configured/implemented in example embodimentsof the disclosure.

In the case of DC, the UE may be configured with two MAC entities: oneMAC entity for MeNB, and one MAC entity for SeNB. In DC, the configuredset of serving cells for a UE may comprise two subsets: the Master CellGroup (MCG) containing the serving cells of the MeNB, and the SecondaryCell Group (SCG) containing the serving cells of the SeNB. For a SCG,one or more of the following may be applied. At least one cell in theSCG may have a configured UL CC and one of them, named PSCell (or PCellof SCG, or sometimes called PCell), may be configured with PUCCHresources. When the SCG is configured, there may be at least one SCGbearer or one Split bearer. Upon detection of a physical layer problemor a random access problem on a PSCell, or the maximum number of RLCretransmissions has been reached associated with the SCG, or upondetection of an access problem on a PSCell during a SCG addition or aSCG change: a RRC connection re-establishment procedure may not betriggered, UL transmissions towards cells of the SCG may be stopped, anda MeNB may be informed by the UE of a SCG failure type. For splitbearer, the DL data transfer over the MeNB may be maintained. The RLC AMbearer may be configured for the split bearer. Like a PCell, a PSCellmay not be de-activated. A PSCell may be changed with a SCG change (forexample, with a security key change and a RACH procedure), and/orneither a direct bearer type change between a Split bearer and a SCGbearer nor simultaneous configuration of a SCG and a Split bearer may besupported.

With respect to the interaction between a MeNB and a SeNB, one or moreof the following principles may be applied. The MeNB may maintain theRRM measurement configuration of the UE and may, (for example, based onreceived measurement reports or traffic conditions or bearer types),decide to ask a SeNB to provide additional resources (serving cells) fora UE. Upon receiving a request from the MeNB, a SeNB may create acontainer that may result in the configuration of additional servingcells for the UE (or decide that it has no resource available to do so).For UE capability coordination, the MeNB may provide (part of) the ASconfiguration and the UE capabilities to the SeNB. The MeNB and the SeNBmay exchange information about a UE configuration by employing RRCcontainers (inter-node messages) carried in X2 messages. The SeNB mayinitiate a reconfiguration of its existing serving cells (for example, aPUCCH towards the SeNB). The SeNB may decide which cell is the PSCellwithin the SCG. The MeNB may not change the content of the RRCconfiguration provided by the SeNB. In the case of a SCG addition and aSCG SCell addition, the MeNB may provide the latest measurement resultsfor the SCG cell(s). Both a MeNB and a SeNB may know the SFN andsubframe offset of each other by OAM, (for example, for the purpose ofDRX alignment and identification of a measurement gap). In an example,when adding a new SCG SCell, dedicated RRC signaling may be used forsending required system information of the cell as for CA, except forthe SFN acquired from a MIB of the PSCell of a SCG.

In an example, serving cells may be grouped in a TA group (TAG). Servingcells in one TAG may use the same timing reference. For a given TAG,user equipment (UE) may use at least one downlink carrier as a timingreference. For a given TAG, a UE may synchronize uplink subframe andframe transmission timing of uplink carriers belonging to the same TAG.In an example, serving cells having an uplink to which the same TAapplies may correspond to serving cells hosted by the same receiver. AUE supporting multiple TAs may support two or more TA groups. One TAgroup may contain the PCell and may be called a primary TAG (pTAG). In amultiple TAG configuration, at least one TA group may not contain thePCell and may be called a secondary TAG (sTAG). In an example, carrierswithin the same TA group may use the same TA value and/or the sametiming reference. When DC is configured, cells belonging to a cell group(MCG or SCG) may be grouped into multiple TAGs including a pTAG and oneor more sTAGs.

FIG. 8 shows example TAG configurations as per an aspect of anembodiment of the present disclosure. In Example 1, pTAG comprises aPCell, and an sTAG comprises SCell1. In Example 2, a pTAG comprises aPCell and SCell1, and an sTAG comprises SCell2 and SCell3. In Example 3,pTAG comprises PCell and SCell1, and an sTAG1 includes SCell2 andSCell3, and sTAG2 comprises SCell4. Up to four TAGs may be supported ina cell group (MCG or SCG) and other example TAG configurations may alsobe provided. In various examples in this disclosure, example mechanismsare described for a pTAG and an sTAG. Some of the example mechanisms maybe applied to configurations with multiple sTAGs.

In an example, an eNB may initiate an RA procedure via a PDCCH order foran activated SCell. This PDCCH order may be sent on a scheduling cell ofthis SCell. When cross carrier scheduling is configured for a cell, thescheduling cell may be different than the cell that is employed forpreamble transmission, and the PDCCH order may include an SCell index.At least a non-contention based RA procedure may be supported forSCell(s) assigned to sTAG(s).

FIG. 9 is an example message flow in a random access process in asecondary TAG as per an aspect of an embodiment of the presentdisclosure. An eNB transmits an activation command 600 to activate anSCell. A preamble 602 (Msg1) may be sent by a UE in response to a PDCCHorder 601 on an SCell belonging to an sTAG. In an example embodiment,preamble transmission for SCells may be controlled by the network usingPDCCH format 1A. Msg2 message 603 (RAR: random access response) inresponse to the preamble transmission on the SCell may be addressed toRA-RNTI in a PCell common search space (CSS). Uplink packets 604 may betransmitted on the SCell in which the preamble was transmitted.

According to an embodiment, initial timing alignment may be achievedthrough a random access procedure. This may involve a UE transmitting arandom access preamble and an eNB responding with an initial TA commandNTA (amount of timing advance) within a random access response window.The start of the random access preamble may be aligned with the start ofa corresponding uplink subframe at the UE assuming NTA=0. The eNB mayestimate the uplink timing from the random access preamble transmittedby the UE. The TA command may be derived by the eNB based on theestimation of the difference between the desired UL timing and theactual UL timing. The UE may determine the initial uplink transmissiontiming relative to the corresponding downlink of the sTAG on which thepreamble is transmitted.

The mapping of a serving cell to a TAG may be configured by a servingeNB with RRC signaling. The mechanism for TAG configuration andreconfiguration may be based on RRC signaling. According to variousaspects of an embodiment, when an eNB performs an SCell additionconfiguration, the related TAG configuration may be configured for theSCell. In an example embodiment, an eNB may modify the TAG configurationof an SCell by removing (releasing) the SCell and adding (configuring) anew SCell (with the same physical cell ID and frequency) with an updatedTAG ID. The new SCell with the updated TAG ID may initially be inactivesubsequent to being assigned the updated TAG ID. The eNB may activatethe updated new SCell and start scheduling packets on the activatedSCell. In an example implementation, it may not be possible to changethe TAG associated with an SCell, but rather, the SCell may need to beremoved and a new SCell may need to be added with another TAG. Forexample, if there is a need to move an SCell from an sTAG to a pTAG, atleast one RRC message, (for example, at least one RRC reconfigurationmessage), may be send to the UE to reconfigure TAG configurations byreleasing the SCell and then configuring the SCell as a part of thepTAG. Wwhen an SCell is added/configured without a TAG index, the SCellmay be explicitly assigned to the pTAG. The PCell may not change its TAgroup and may be a member of the pTAG.

The purpose of an RRC connection reconfiguration procedure may be tomodify an RRC connection, (for example, to establish, modify and/orrelease RBs, to perform handover, to setup, modify, and/or releasemeasurements, to add, modify, and/or release SCells). If the receivedRRC Connection Reconfiguration message includes the sCellToReleaseList,the UE may perform an SCell release. If the received RRC ConnectionReconfiguration message includes the sCellToAddModList, the UE mayperform SCell additions or modification.

In LTE Release-10 and Release-11 CA, a PUCCH may only be transmitted onthe PCell (PSCell) to an eNB. In LTE-Release 12 and earlier, a UE maytransmit PUCCH information on one cell (PCell or PSCell) to a given eNB.

As the number of CA capable UEs and also the number of aggregatedcarriers increase, the number of PUCCHs and also the PUCCH payload sizemay increase. Accommodating the PUCCH transmissions on the PCell maylead to a high PUCCH load on the PCell. A PUCCH on an SCell may beintroduced to offload the PUCCH resource from the PCell. More than onePUCCH may be configured for example, a PUCCH on a PCell and anotherPUCCH on an SCell. In the example embodiments, one, two or more cellsmay be configured with PUCCH resources for transmitting CSI/ACK/NACK toa base station. Cells may be grouped into multiple PUCCH groups, and oneor more cell within a group may be configured with a PUCCH. In anexample configuration, one SCell may belong to one PUCCH group. SCellswith a configured PUCCH transmitted to a base station may be called aPUCCH SCell, and a cell group with a common PUCCH resource transmittedto the same base station may be called a PUCCH group.

In an example embodiment, a MAC entity may have a configurable timertimeAlignmentTimer per TAG. The timeAlignmentTimer may be used tocontrol how long the MAC entity considers the Serving Cells belonging tothe associated TAG to be uplink time aligned. The MAC entity may, when aTiming Advance Command MAC control element is received, apply the TimingAdvance Command for the indicated TAG; start or restart thetimeAlignmentTimer associated with the indicated TAG. The MAC entitymay, when a Timing Advance Command is received in a Random AccessResponse message for a serving cell belonging to a TAG and/orif theRandom Access Preamble was not selected by the MAC entity, apply theTiming Advance Command for this TAG and start or restart thetimeAlignmentTimer associated with this TAG. Otherwise, if thetimeAlignmentTimer associated with this TAG is not running, the TimingAdvance Command for this TAG may be applied and the timeAlignmentTimerassociated with this TAG started. When the contention resolution isconsidered not successful, a timeAlignmentTimer associated with this TAGmay be stopped. Otherwise, the MAC entity may ignore the received TimingAdvance Command.

In example embodiments, a timer is running once it is started, until itis stopped or until it expires; otherwise it may not be running A timercan be started if it is not running or restarted if it is running. Forexample, a timer may be started or restarted from its initial value.

Example embodiments of the disclosure may enable operation ofmulti-carrier communications. Other example embodiments may comprise anon-transitory tangible computer readable media comprising instructionsexecutable by one or more processors to cause operation of multi-carriercommunications. Yet other example embodiments may comprise an article ofmanufacture that comprises a non-transitory tangible computer readablemachine-accessible medium having instructions encoded thereon forenabling programmable hardware to cause a device (e.g. wirelesscommunicator, UE, base station, etc.) to enable operation ofmulti-carrier communications. The device may include processors, memory,interfaces, and/or the like. Other example embodiments may comprisecommunication networks comprising devices such as base stations,wireless devices (or user equipment: UE), servers, switches, antennas,and/or the like.

The amount of data traffic carried over cellular networks is expected toincrease for many years to come. The number of users/devices isincreasing and each user/device accesses an increasing number andvariety of services, e.g. video delivery, large files, images. This mayrequire not only high capacity in the network, but also provisioningvery high data rates to meet customers' expectations on interactivityand responsiveness. More spectrum may therefore needed for cellularoperators to meet the increasing demand Considering user expectations ofhigh data rates along with seamless mobility, it may be beneficial thatmore spectrum be made available for deploying macro cells as well assmall cells for cellular systems.

Striving to meet the market demands, there has been increasing interestfrom operators in deploying some complementary access utilizingunlicensed spectrum to meet the traffic growth. This is exemplified bythe large number of operator-deployed Wi-Fi networks and the 3GPPstandardization of LTE/WLAN interworking solutions. This interestindicates that unlicensed spectrum, when present, may be an effectivecomplement to licensed spectrum for cellular operators to helpaddressing the traffic explosion in some scenarios, such as hotspotareas. LAA may offer an alternative for operators to make use ofunlicensed spectrum while managing one radio network, thus offering newpossibilities for optimizing the network's efficiency.

In an example embodiment, Listen-before-talk (clear channel assessment)may be implemented for transmission in an LAA cell. In alisten-before-talk (LBT) procedure, equipment may apply a clear channelassessment (CCA) check before using the channel. For example, the CCAmay utilize at least energy detection to determine the presence orabsence of other signals on a channel in order to determine if a channelis occupied or clear, respectively. For example, European and Japaneseregulations mandate the usage of LBT in the unlicensed bands. Apart fromregulatory requirements, carrier sensing via LBT may be one way for fairsharing of the unlicensed spectrum.

In an example embodiment, discontinuous transmission on an unlicensedcarrier with limited maximum transmission duration may be enabled. Someof these functions may be supported by one or more signals to betransmitted from the beginning of a discontinuous LAA downlinktransmission. Channel reservation may be enabled by the transmission ofsignals, by an LAA node, after gaining channel access via a successfulLBT operation, so that other nodes that receive the transmitted signalwith energy above a certain threshold sense the channel to be occupied.Functions that may need to be supported by one or more signals for LAAoperation with discontinuous downlink transmission may include one ormore of the following: detection of the LAA downlink transmission(including cell identification) by UEs, time & frequency synchronizationof UEs, and/or the like.

In an example embodiment, a DL LAA design may employ subframe boundaryalignment according to LTE-A carrier aggregation timing relationshipsacross serving cells aggregated by CA. This may not imply that the eNBtransmissions can start only at the subframe boundary. LAA may supporttransmitting PDSCH when not all OFDM symbols are available fortransmission in a subframe according to LBT. Delivery of necessarycontrol information for the PDSCH may also be supported.

An LBT procedure may be employed for fair and friendly coexistence ofLAA with other operators and technologies operating in an unlicensedspectrum. LBT procedures on a node attempting to transmit on a carrierin an unlicensed spectrum may require the node to perform a clearchannel assessment to determine if the channel is free for use. An LBTprocedure may involve at least energy detection to determine if thechannel is being used. For example, regulatory requirements in someregions, for example, in Europe, may specify an energy detectionthreshold such that if a node receives energy greater than thisthreshold, the node assumes that the channel is not free. While nodesmay follow such regulatory requirements, a node may optionally use alower threshold for energy detection than that specified by regulatoryrequirements. In an example, LAA may employ a mechanism to adaptivelychange the energy detection threshold. For example, LAA may employ amechanism to adaptively lower the energy detection threshold from anupper bound. Adaptation mechanism(s) may not preclude static orsemi-static setting of the threshold. In an example a Category 4 LBTmechanism or other type of LBT mechanisms may be implemented.

Various example LBT mechanisms may be implemented. In an example, forsome signals, in some implementation scenarios, in some situations,and/or in some frequencies, no LBT procedure may performed by thetransmitting entity. In an example, Category 2 (for example, LBT withoutrandom back-off) may be implemented. The duration of time that thechannel is sensed to be idle before the transmitting entity transmitsmay be deterministic. In an example, Category 3 (for example, LBT withrandom back-off with a contention window of fixed size) may beimplemented. The LBT procedure may have the following procedure as oneof its components. The transmitting entity may draw a random number Nwithin a contention window. The size of the contention window may bespecified by the minimum and maximum value of N. The size of thecontention window may be fixed. The random number N may be employed inthe LBT procedure to determine the duration of time that the channel issensed to be idle before the transmitting entity transmits on thechannel. In an example, Category 4 (for example, LBT with randomback-off with a contention window of variable size) may be implemented.The transmitting entity may draw a random number N within a contentionwindow. The size of the contention window may be specified by a minimumand maximum value of N. The transmitting entity may vary the size of thecontention window when drawing the random number N. The random number Nmay be employed in the LBT procedure to determine the duration of timethat the channel is sensed to be idle before the transmitting entitytransmits on the channel.

LAA may employ uplink LBT at the UE. The UL LBT scheme may be differentfrom the DL LBT scheme (for example, by using different LBT mechanismsor parameters), since the LAA UL may be based on scheduled access whichaffects a UE's channel contention opportunities. Other considerationsmotivating a different UL LBT scheme include, but are not limited to,multiplexing of multiple UEs in a single subframe.

In an example, a DL transmission burst may be a continuous transmissionfrom a DL transmitting node with no transmission immediately before orafter from the same node on the same CC. A UL transmission burst from aUE perspective may be a continuous transmission from a UE with notransmission immediately before or after from the same UE on the sameCC. In an example, a UL transmission burst may be defined from a UEperspective. In an example, a UL transmission burst may be defined froman eNB perspective. In an example, in case of an eNB operating DL+UL LAAover the same unlicensed carrier, DL transmission burst(s) and ULtransmission burst(s) on LAA may be scheduled in a TDM manner over thesame unlicensed carrier. For example, an instant in time may be part ofa DL transmission burst or an UL transmission burst.

In an example embodiment, in an unlicensed cell, a downlink burst may bestarted in a subframe. When an eNB accesses the channel, the eNB maytransmit for a duration of one or more subframes. The duration maydepend on a maximum configured burst duration in an eNB, the dataavailable for transmission, and/or eNB scheduling algorithm. FIG. 10shows an example downlink burst in an unlicensed (e.g. licensed assistedaccess) cell. The maximum configured burst duration in the exampleembodiment may be configured in the eNB. An eNB may transmit the maximumconfigured burst duration to a UE employing an RRC configurationmessage.

The wireless device may receive from a base station at least one message(for example, an RRC) comprising configuration parameters of a pluralityof cells. The plurality of cells may comprise at least one license celland at least one unlicensed (for example, an LAA cell). Theconfiguration parameters of a cell may, for example, compriseconfiguration parameters for physical channels, (for example, a ePDCCH,PDSCH, PUSCH, PUCCH and/or the like).

In an example embodiments, LTE transmission time may include frames, anda frame may include many subframes. The size of various time domainfields in the time domain may be expressed as a number of time unitsT_(s)=1/(15000×2048) seconds. Downlink, uplink and sidelinktransmissions may be organized into radio frames withT_(f)=307200×T_(s)=10 ms duration. In an example LTE implementation, atleast three radio frame structures may be supported: Type 1, applicableto FDD, Type 2, applicable to TDD, Type 3, applicable to LAA secondarycell operation. LAA secondary cell operation applies to frame structuretype 3.

Transmissions in multiple cells may be aggregated where one or moresecondary cells may be used in addition to the primary cell. In case ofmulti-cell aggregation, different frame structures may be used in thedifferent serving cells.

Frame structure type 1 may be applicable to both full duplex and halfduplex FDD. A radio frame is T_(f)=307200·T_(s)=10 ms long and maycomprise 20 slots of length T_(slot)=15360·T_(s)=0.5 ms, numbered from 0to 19. A subframe may include two consecutive slots where subframe icomprises of slots 2i and 2i+1.

For FDD, 10 subframes are available for downlink transmission and 10subframes are available for uplink transmissions in a 10 ms interval.Uplink and downlink transmissions are separated in the frequency domain.In half-duplex FDD operation, the UE may not transmit and receive at thesame time while there may not be such restrictions in full-duplex FDD.

Frame structure type 2 may be applicable to TDD. A radio frame of lengthT_(f)=307200·T_(s)=10 ms may comprise of two half-frames of length153600·T=5 ms. A half-frame may comprise five subframes of length30720·T_(s)=1 ms. A subframe i may comprise two slots, 2i and 2i+1, oflength T_(slot)=15360 T_(s)=0.5 ms.

The uplink-downlink configuration in a cell may vary between frames andcontrols in which subframes uplink or downlink transmissions may takeplace in the current frame. The uplink-downlink configuration in thecurrent frame is obtained via control signaling.

An example subframe in a radio frame, “may be a downlink subframereserved for downlink transmissions, may be an uplink subframe reservedfor uplink transmissions or may be a special subframe with the threefields DwPTS, GP and UpPTS. The length of DwPTS and UpPTS are subject tothe total length of DwPTS, GP and UpPTS being equal to 30720·T_(s)=1 ms.

Uplink-downlink configurations with both 5 ms and 10 msdownlink-to-uplink switch-point periodicity may be supported. In case of5 ms downlink-to-uplink switch-point periodicity, the special subframemay exist in both half-frames. In case of 10 ms downlink-to-uplinkswitch-point periodicity, the special subframe may exist in the firsthalf-frame.

Subframes 0 and 5 and DwPTS may be reserved for downlink transmission.UpPTS and the subframe immediately following the special subframe may bereserved for uplink transmission.

In an example, in case multiple cells are aggregated, the UE may assumethat the guard period of the special subframe in the cells using framestructure Type 2 have an overlap of at least 1456·T_(s).

In an example, in case multiple cells with different uplink-downlinkconfigurations in the current radio frame are aggregated and the UE isnot capable of simultaneous reception and transmission in the aggregatedcells, the following constraints may apply. if the subframe in theprimary cell is a downlink subframe, the UE may not transmit any signalor channel on a secondary cell in the same subframe. If the subframe inthe primary cell is an uplink subframe, the UE may not be expected toreceive any downlink transmissions on a secondary cell in the samesubframe. If the subframe in the primary cell is a special subframe andthe same subframe in a secondary cell is a downlink subframe, the UE maynot be expected to receive PDSCH/EPDCCH/PMCH/PRS transmissions in thesecondary cell in the same subframe, and the UE may not be expected toreceive any other signals on the secondary cell in OFDM symbols thatoverlaps with the guard period or UpPTS in the primary cell.

Frame structure type 3 may be applicable to LAA secondary cell operationwith normal cyclic prefix. A radio frame is T_(f)=307200·T_(s)=10 mslong and comprises of 20 slots of length T_(slot) 15360·T_(s)=0.5 msnumbered from 0 to 19. A subframe may comprise as two consecutive slotswhere subframe i comprises slots 2i and 2i+1.

The 10 subframes within a radio frame are available for downlinktransmissions. Downlink transmissions occupy one or more consecutivesubframes, starting anywhere within a subframe and ending with the lastsubframe either fully occupied or following one of the DwPTS durations.Subframes may be available for uplink transmission when LAA uplink issupported.

In an LAA cell, uplink transmission timing is advanced by N_TA as shownin FIG. 16. A UE advances its transmission timing based on TAC receivedfrom the eNB, e.g. to compensate for round-trip propagation delay. Thismay imply that from a UE transmitter uplink subframe timing starts andends earlier than downlink subframes. A guard period is needed whendownlink transmission ends and uplink transmission starts in a UE. TheeNB may not be able to calculate the exact N_TA amount, since the UE mayautonomously change the N_TA in some scenarios. A guard period may berequired so that uplink and downlink transmission timings do not overlapin a TDD system. In addition, LBT period for a UE may create atransmission gap between downlink transmission and uplink transmission.FIG. 11 shows an example uplink and downlink timings in a UE.

In an example embodiment, the guard period/LBT may provide atransmission gap. Other UEs/nodes (e.g. Wifi nodes) may acquire thechannel after downlink transmission ends, and during thetransmission/LBT gap. This may not allow a UE to acquire the channel andtransmit uplink signals when the UE is granted an uplink resource aftera downlink burst. Transmission of reservation signals by a UE may enableto reserve the channel and reduce the possibility of losing a channel.

In an LAA system, when an eNB transmits a full downlink subframe, thenext available subframe for uplink transmission may be a partial uplinksubframe due to transmission gap, NTA requirements, and/or LBT process.In an LAA system, when an eNB transmits an end partial downlinksubframe, the next available subframe for uplink transmission may be afull or partial uplink subframe due to transmission gap, NTArequirements, and/or LBT.

In an example implementation, cells in a first group of multiple LAAcells may be aggregated and a UE may not be capable of simultaneousreception and transmission in the aggregated LAA cells. For example, thecells may be in the same band. For example, the cells may be in adjacentfrequencies in the same band. This may be due to a software and/orhardware limitation in the wireless device.

Some or all of the cells in the first group of the multiple LAA cellsmay be capable of simultaneous reception and transmission with the PCelland/or other licensed cells. For example, an LAA cell in the first groupmay be able to transmit signals while receiving signals on a PCell. Inthis case, applying constraints to the UE on transmission and receptionof signals on LAA based on the state of the PCell (downlink, uplink, orspecial subframe) seems to be an inefficient and sub-optimal solution.

In an example, a second group of multiple LAA cells different from thefirst group may be configured. The second group of multiple LAA cellsmay be aggregated and a UE may not be capable of simultaneous receptionand transmission in the aggregated LAA cells of the second group. Forexample, the cells in the same cell group may be in the same band. Forexample, the cells may be adjacent in frequency in the same band.

A cell in the first group may transmit signals while a cell in thesecond group is receiving signals, and vice versa. For example, cells inthe first group may be in a first band and the cells in the second groupmay be in a second band. For example, cells in the first group mayemploy a first transceiver and cells in the second group may employ asecond transceiver. The example embodiments may separately apply to afirst group and a second group.

In an example implementation, the cells in the first group may be havetheir own limitations with respect to simultaneous reception andtransmission in the aggregated cells of the first group. In an exampleimplementation, the cells in the second group may be have their ownlimitations with respect to simultaneous reception and transmission inthe aggregated cells of the second group. Cells in different licensedbands may have their own constraints on simultaneous reception andtransmission in the aggregated cells.

In an implementation, cells may be grouped according to theirlimitations on simultaneous reception and transmission in the aggregatedcells.

In an example embodiment, a UE may not assume that LAA cells may followthe same uplink and downlink subframes as the PCell. A PCell may employframe structure Type 1 or 2, while an LAA cell may employ framestructure Type 3. In an example embodiment, constraints are introducedfor a UE and/or eNB for cells in a group to reduce the transmit and/orreceive possibilities. This may reduce unnecessary signal processing inthe UE and/or eNB. The constraints may be employed by the UE and/or eNBto reduce battery power consumption in the UE and/or eNB. Theconstraints may be applicable to the cells within a cell group, forexample, the cells in the licensed band, a first group of cells in anunlicensed band A, a second group of cells in an unlicensed band B, etc.Example embodiments improve LAA cell efficiency and reduces UE batterypower consumption and reduces UE processing requirements.

In an example embodiment, cells may be grouped based on simultaneousreception and transmission in the aggregated cells in a group. A UE maynot be capable of simultaneous reception and transmission in theaggregated cells within a cell group.

In an example embodiment, a UE may transmit an RRC message (e.g. UEcapability message) to the eNB. The message may comprise one or moreparameters indicating the UE capability with respect to the example cellgrouping. For example, the one or more parameters may indicate certainfrequency bands, in which cells are grouped within a cell group. Forexample, the one or more parameters may comprise a set of frequenciesthat are in a cell group. For example, the one or more parameters may bea transceiver parameter in the UE indicating the frequency bands inwhich cells may be grouped. For example, the one or more parameters mayindicate a device category or certain capability that indicate thelimitation on cell aggregation to the UE.

In an example, such an aggregation limitation in different cell groupsmay be a characteristic of the UE, and an eNB may not be informed aboutsuch limitation. In an example embodiment, the aggregation limitationmay be pre-specified in both eNB and UE based on bands, cellfrequencies, cell bandwidth, and/or other parameters.

In an example, an eNB may configure the cell grouping in the UE. An eNBmay transmit one or more messages to the UE configuring cell groupingbased on simultaneous reception and transmission capability in theaggregated cells within a cell group. For example, an eNB may transmitone or more RRC messages comprising cell indexes of a cell group (e.g.identified by a group index). The one or more RRC message may associatethe cells with a group, e.g. using a cell group index.

In an example embodiment, a cell in a group may be considered a leadcell. A lead cell may be preconfigured by an RRC message. An RRC messagemay comprise one or more parameters, e.g. a cell index, of a cell in acell group. In an example, an RRC may comprise one or more configurationparameters for an SCell that implicitly or explicitly indicates that thecell is a lead cell in a group. In an example, the lead cell may bedetermined according to a predefined rule, for example the cell with alowest cell index, and/or the like. The predefined rule may beconfigured in a UE and/or an eNB.

In an example embodiment, the lead cell may be identified by a UE on asubframe by subframe basis. In an example embodiment, there is no needto select a lead cell, and a collective constraint may be applied to thecells in a group at any moment. In an example, the cell that has certaincharacteristics at a moment (e.g. eNB is transmitting, UE istransmitting) may determine the status of other cells. In an example, alead cell may be any cell in a cell group.

In an example implementation, when a UE is not capable of receivingdownlink signals in a group at certain time, the UE may not decodedownlink signals of cells of a group at that certain time. The UE maynot blind decode the downlink cell and/or search for downlink signals.The UE may not expect to receive and monitor downlink signals such assynchronization signals, DRS, control channels (PCFICH, PDCCH, ePDCCH,PDSCH, and/or CRS, etc). This may reduce the battery power consumptionin the UE, since the UE may not decode the receive signals. For example,the UE may turn off the receiver on one or more cells in a group. The UEmay selectively monitor downlink signals/channels of a subframe based ondownlink and uplink transmissions in another cell in the group.

An example scenario is described below. The lead cell may be any one ofthe activated cells within a group.

Example status of a lead cell in a group: downlink transmission, thenexample UE capability in other cells of the group may be one or more ofthe following: Can receive downlink signals; Cannot transmit uplinksignals; Can perform LBT for uplink transmission; UE may be during aguard period (e.g. DL to UL transition period).

Example status of a lead cell in a group: idle (no DL/UL transmission),then Example UE capability in other cells of the group may be one ormore of the following: Can receive downlink signals; Can transmit uplinksignals; Can perform LBT for uplink transmission; UE may be during aguard period (e.g. DL to UL transition period, or UL to DL transitionperiod).

Example status of a lead cell in a group: Uplink transmission, thenExample UE capability in other cells of the group may be one or more ofthe following: Cannot receive downlink signals; Can transmit uplinksignals; Can perform LBT for uplink transmission (e.g. with a differentthreshold); UE may be during a guard period (e.g. UL to DL transitionperiod).

In an example, the lead cell may be any one of the activated cellswithin a group. In the following examples, the state of a full subframeis described.

Status of a lead cell during the full subframe n: downlink transmission,then UE capability in other cells of the group may be one or more of thefollowing: Subframe n can be downlink; Subframe n can be an ending(partial) uplink subframe (e.g. depending on configuration); subframen+1 can be a beginning (partial) uplink subframe (e.g. depending onconfiguration); Can perform LBT for uplink transmission for a beginning(partial) uplink subframe in subframe n+1 (e.g. depending onconfiguration); UE may be during a guard period (e.g. DL to ULtransition period).

Status of a lead cell during the full subframe n: idle period, then UEcapability in other cells of the group may be one or more of thefollowing: Can receive downlink signals; Can transmit uplink signals;Can perform LBT for uplink transmission; UE may be during a guard period(e.g. DL to UL transition period, or UL to DL transition period).

Status of a lead cell during the full subframe n: uplink transmission,then UE capability in other cells of the group may be one or more of thefollowing: Can receive downlink reservation signals during an end periodof subframe n, can receive downlink beginning partial subframe (e.g.depending on configuration, and/or N_TA); Can transmit uplink signals;Can perform LBT for uplink transmission (e.g. with a differentthreshold); UE may be during the guard period (e.g. UL to DL transitionperiod).

For example, when subframe n is a full downlink subframe, a UE mayreceive downlink signals in other cells of the cell group in subframe n.Depending on implementation, subframe n may be capable of being anending (partial) uplink subframe (e.g. depend on TA values and/orwhether implementation of ending partial uplink subframe is allowed).Subframe n+1 can be a beginning (partial) uplink subframe (e.g. dependon TA values and/or whether implementation of beginning partial uplinksubframe is allowed). For example, in an implementation the second slotof subframe n+1 may be employed for uplink transmission. In an example,if a UE transmitting signals in full subframe k in a cell in response toa grant, the UE may not monitor downlink control channels in subframe kon other cells.

In an example embodiment, a detected downlink burst may determine thestatus of the cells in a group. For example, when a UE starts receivinga downlink burst in a subframe, the UE may assume that the cells in thegroup are in downlink transmission mode, until the last downlinktransmission burst on the last cell ends. The UE may not transmit anysignals until the downlink transmission from the eNB continues. Afterthe UE detects the last downlink transmission on one or the cells, theUE may start LBT for uplink transmission (e.g. if the UE has an uplinkgrant, or needs to transmit an SRS, PRACH, etc).

In an example, when a UE starts transmission of an uplink burst in asubframe, the UE may assume that the cells are in uplink transmissionmode, until the last uplink TB is transmitted on a last cell. During theuplink transmission on a cell, the UE may not monitor downlink signalson other cells until uplink transmission on a last cell ends. Forexample, the UE may not monitor downlink control channel, synch signal,DRS and other downlink signals on a cell when the UE is transmitting onanother cell in the group.

When a subframe is a partial subframe, the status of other cells in thesubframe and subsequent subframes may depend on the duration of thetransmission during the partial subframe and whether the partialsubframe is a beginning subframe or an ending subframe. Some examplescenarios are described below.

Status of a lead cell during a partial subframe n: downlink end partialtransmission, then UE capability in other cells of the group may be oneor more of the following: Subframe n can be downlink, Subframe n can bean ending (partial) uplink subframe (e.g. depending on configuration,and/or N_TA), subframe n+1 can be a beginning (partial or full) uplinksubframe (e.g. depending on partial subframe length, configuration,and/or N_TA), Can perform LBT for uplink transmission for a beginning(partial or full) uplink subframe (e.g. depending on partial subframelength, configuration, and/or N_TA), UE may be during a guard period(e.g. DL to UL transition period).

Status of a lead cell during a partial subframe n: downlink beginningpartial transmission, then UE capability in other cells of the group maybe one or more of the following: Subframe n can be downlink; Subframe ncan be an ending (partial) uplink subframe, subframe n+1 can be abeginning (partial) uplink subframe or no uplink (e.g. depending onpartial subframe length, configuration, and/or N_TA).

In an example embodiment, similar constraints may be applied to eNB.This process may reduce battery power consumption in the eNB. Groupingsmay provide scheduling constraints in the eNB for downlink transmissionand uplink reception similar to the constraints in the UE.

Some example embodiments are shown in FIGS. 12 to 15. In examplefigures, a limited number of downlink bursts and uplink bursts areshown. In an example, an uplink burst or downlink burst may be one ormore transmission bursts.

In an example embodiment as shown in FIG. 12, downlink transmission maystart at the same or different starting time in different cells (e.g.depending on scheduling, LBT, configuration, etc.). For example, LBT maydetect an interference in cell2 until the start of DL2 burst, and LBT incell1 indicate a clear channel earlier. For example, eNB may startscheduling downlink information on cell2 later than cell1. The eNB maytransmit downlink signals and UE may receive downlink signals until thelast downlink burst in a cell is ended, e.g. DL3 (the UE is in downlinkmode). Then the UE may start uplink transmission, if UE is granteduplink resources. In an example, the UE may transmit uplink until thelast uplink burst is ended, e.g. UL3 (the UE is in uplink mode). The UEmay not transmit any signal when it is in downlink mode. The UE may notreceive any signal and may not decode downlink control signals when itis in uplink mode. FIG. 12 is an example, in some scenarios, some of thecells may not be scheduled for downlink or uplink transmission. Forexample, consider FIG. 12 and when DL2 or UL1 may not be transmitted.

Another example is shown in FIG. 13. FIG. 13 illustrates a scenario,wherein LAA cell1 transmits two downlink bursts. In FIG. 13, LAA cell 1is the cell with a downlink that last longer.

In an example embodiment as shown in FIG. 14, downlink bursts on one ormore cells may end substantially at the same time, and/or in the samesubframe. In an example the downlink burst that started first maydetermine when the COT is ended. In an example, this cell may be thelead cell. Other downlink transmission bursts may start later (DL2 andDL3), but may end at the same time as DL1 or earlier than DL1 (e.g. whenthere is no data to be transmitted on DL3, DL3 may end earlier). In anexample, the same concept may apply to uplink transmissions. The uplinkburst that started first may determine the beginning of an uplink burst.The COT may be determined from the time that UL1 has started and may endwhen UL2/UL3 is ended.

In an example embodiment as shown in FIG. 15, downlink and/or uplinktransmission on multiple cells may start at the same time. For example,the eNB may start downlink transmission on multiple cells, when LBTclears on one or more cells. For example, in the figures DL1, DL2, andDL3 started at the same time. In an example, if LBT of a cell does notindicate clear channel, the eNB may not transmit a downlink signal onthe cell. In an example, if LBT of a cell does not indicate a clearchannel, the eNb may defer transmission on other cell for certainperiod. In an example, eNB may decide on whether it should defertransmission on cells or transmit on some of the cells and not totransmit on some other cells. The downlink bursts may end at differenttimes, depending on scheduling method and available downlink data. Thesame may apply to uplink. For example, UL1 and UL3 started at the sametime, but may end at different times. The eNB may not have scheduleddata for cell2 in the uplink, or LBT in the UE may not have indicated aclear channel.

In an example embodiment, a cell may be configured or selected as a leadcell, and other cells in a group may follow the status of the lead cell.In an example embodiment, one or more RRC message may comprise one ormore parameters indicating the configuration parameters of downlink anduplink transmission parameter and may determine one or more modes asdescribed above is operated by a UE and/or eNB.

In an example embodiment, the examples in FIG. 12 to FIG. 15 may beextended to illustrate the operations of an eNB. For example, an eNB maynot decode signals from a UE, when it is in a downlink transmissionmode. For example, an eNB may not transmit any signals to any UE, whenit is in the receive mode. The constraints described in the exampleembodiments may be extended to the operations on an eNB. The constraintsmay be employed by an eNB scheduler to schedule uplink and downlink TBs.for example, an eNB may not schedule uplink TB on cell1 and downlink TBon cell1.

Example embodiments may be deployed to resolve conflicting situations ina UE. For example, when a UE is scheduled to transmit a TB in subframen, but the UE receives indication of downlink eNB signals in subframen−1 and/or subframe n, the UE may decide to ignore the downlink signalor transmit the uplink grant. In an example embodiment, the UE mayconsider that downlink transmission from an eNB may have priority overuplink transmission from the UE. For example, when the UE detectsdownlink transmission for an eNB in subframe n, the UE may consider thatthe subframe n is a downlink subframe. The UE may ignore conflictinguplink grants and ignore a scheduled uplink transmission (e.g. SRS,data, control, PRACH, etc). In an example, when eNB has already starteduplink transmission, it may not be able to detect downlink signalstransmitted from the UE during its uplink transmission in the cellgroup.

In an example embodiment, an eNB may schedule downlink and uplink TBsaccording to the constraints described in the embodiment. The UE maytransmit or receive signals according to the (e)PDCCH scheduling grantsreceived from the eNB. The UE and/or eNB may employ the constraintsdescribed in the example embodiment to reduce the required processing ofsignals and reduce battery power consumption.

A UE and/or eNB may configure a timer and/or a counter tracking thecontinuous transmission in a burst. A UE and/or eNB may start the timerwhen it starts transmission and/or reception. This may allow the UEand/or an eNB when an uplink and/or downlink transmission burst may end.The UE and/or eNB may subsequently base its downlink and/or uplinkprocessing based on the value in the timer. An eNB and/or UE may beallowed to continuously transmit up to a maximum duration. In an exampleembodiment, an eNB may transmit an RRC message to a UE comprising thevalue of the timer/counter.

According to various embodiments, a device such as, for example, awireless device, a base station and/or the like, may comprise one ormore processors and memory. The memory may store instructions that, whenexecuted by the one or more processors, cause the device to perform aseries of actions. Embodiments of example actions are illustrated in theaccompanying figures and specification.

Frame structure type 2 may be applicable to TDD. A radio frame of lengthT_(f)=307200·T_(s)=10 ms may comprise of two half-frames of length153600·T_(s)=5 ms. A half-frame comprises of five subframes of length30720·T_(s)=1 ms. A subframe i is defined as two slots, 2i and 2i+1, oflength T_(slot)=15360·T_(s)=0.5 ms. Subframe i in frame n_(f) has anabsolute subframe number n_(sf) ^(abs)=10n_(f)+i where n_(f) is thesystem frame number.

The uplink-downlink configuration in a cell may vary between frames andcontrols in which subframes uplink or downlink transmissions may takeplace in the current frame.

The supported TDD uplink-downlink configurations are pre-defined in LTEstandards, for a subframe in a radio frame, “D” denotes a downlinksubframe reserved for downlink transmissions, “U” denotes an uplinksubframe reserved for uplink transmissions and “S” denotes a specialsubframe with the three fields DwPTS, GP and UpPTS. The total length ofDwPTS, GP and UpPTS being equal to 30720·T_(s)=1 ms where X is thenumber of additional SC-FDMA symbols in UpPTS provided by the higherlayer parameter srs-UpPtsAdd if configured otherwise X is equal to 0.The UE is not expected to be configured with 2 additional UpPTS SC-FDMAsymbols for special subframe configurations {3, 4, 7, 8} for normalcyclic prefix in downlink and special subframe configurations {2, 3, 5,6} for extended cyclic prefix in downlink and 4 additional UpPTS SC-FDMAsymbols for special subframe configurations {1 2, 3, 4, 6, 7, 8} fornormal cyclic prefix in downlink and special subframe configurations {1,2, 3, 5, 6} for extended cyclic prefix in downlink.

In frame structure 2 (TDD), uplink-downlink configurations with both 5ms and 10 ms downlink-to-uplink switch-point periodicity are supported.In case of 5 ms downlink-to-uplink switch-point periodicity, the specialsubframe may exist in both half-frames. In case of 10 msdownlink-to-uplink switch-point periodicity, the special subframe mayexist in the first half-frame.

In frame structure 2, subframes 0 and 5 and DwPTS may be reserved fordownlink transmission. UpPTS and the subframe immediately following thespecial subframe may be reserved for uplink transmission. In casemultiple cells are aggregated, the UE may assume that the guard periodof the special subframe in the cells using frame structure type 2 havean overlap of at least 1456·T_(s) In an example implementation, the UEis not expected to be configured with 2 additional UpPTS SC-FDMA symbolsfor special subframe configurations {3, 4, 7, 8} for normal cyclicprefix in downlink and 4 additional UpPTS SC-FDMA symbols for specialsubframe configurations {1 2, 3, 4, 6, 7, 8} for normal cyclic prefix indownlink.

An RRC may comprise parameter srs-UpPtsAdd-r13: ENUMERATED {sym2, sym4}.srs-UpPtsAdd may apply for TDD. If E-UTRAN configures bothsoundingRS-UL-ConfigDedicatedUpPTsExt andsoundingRS-UL-ConfigDedicatedAperiodicUpPTsExt, srs-UpPtsAdd in bothfields may be set to the same value.

In a frame structure 2 (TDD), in an example embodiment, an RRC parametermay determine the length of additional UpPTS symbols. The number ofadditional UpPTS symbols may be indicated to the UE with the RRCparameter with two states: {2, 4}. The number of total UpPTS SC-FDMAsymbols may not exceed 6 in a special subframe. The number of DwPTSsymbols may be the number of DwPTS symbols in special subframeconfiguration in SIB1. For trigger types 0 and 1, a set of RRC parametervalues for additional UpPTS may be configured from the legacy SRSconfigurations.

In a frame structure 2 (TDD), tdd-config IE in SIB1 may specify the TDDspecific physical channel configurations. E-UTRAN may set this field tothe same value for instances of SIB1 message that are broadcasted withinthe same cell. In an example LTE implementation, tdd-config may notchange over time. The IE TDD-Config may be defined asTDD-Config::=SEQUENCE {subframeAssignment: ENUMERATED {sa0, sa1, sa2,sa3, sa4, sa5, sa6}, specialSubframePatterns: ENUMERATED {ssp0, ssp1,ssp2, ssp3, ssp4, ssp5, ssp6, ssp7, ssp8}}. In release 11, a new formatis defined for TDD-Config-v1130 IE as TDD-Config-v1130::=SEQUENCE{specialSubframePatterns-v1130: ENUMERATED {ssp7,ssp9}}. In release 12,a new format is defined for TDD-ConfigSL-r12 asTDD-ConfigSL-r12::=SEQUENCE subframeAssignmentSL-r12:ENUMERATED {none,sa0, sa1, sa2, sa3, sa4, sa5, sa6}1.

Frame structure type 3 may be applicable to an LAA cell operation withnormal cyclic prefix. A radio frame is T_(f)=307200·T_(s)=10 ms long andcomprises of 20 slots of length T_(slot)=15360·T_(s)=0.5 ms numberedfrom 0 to 19. A subframe is defined as two consecutive slots wheresubframe i comprises of slots 2i and 2i+1.

The 10 subframes within a radio frame are available for downlinktransmissions. Downlink transmissions may occupy one or more consecutivesubframes, starting anywhere within a subframe and ending with the lastsubframe either fully occupied or following one of the DwPTS durationsin FIG. 19.

UL transmissions on an LAA cell may be supported in release 14 andbeyond. If the legacy special configuration is adopted for a beginningpartial uplink subframe, it may result in example configurations shownin FIG. 19.

In legacy special subframe (Frame structure 2), a UE is not expected tobe configured with 2 additional UpPTS SC-FDMA symbols for specialsubframe configurations {3, 4, 7, 8} for normal cyclic prefix indownlink and 4 additional UpPTS SC-FDMA symbols for special subframeconfigurations {1 2, 3, 4, 6, 7, 8} for normal cyclic prefix indownlink. In the current LTE-Advanced systems, an RRC may compriseparameter srs-UpPtsAdd-r13: ENUMERATED {sym2, sym4}. srs-UpPtsAdd mayapply for TDD. In TDD, if E-UTRAN configures bothsoundingRS-UL-ConfigDedicatedUpPTsExt andsoundingRS-UL-ConfigDedicatedAperiodicUpPTsExt, srs-UpPtsAdd in bothfields may be set to the same value.

If additional UpPTS symbols are configured for SRS, then a new ksrstable may be used to derive SRS transmission instance in extended UpPTS.In an example embodiment, for both trigger type 0 and 1, if a new set ofRRC parameter values for additional UpPTS (e.g.,SoundingRS-UL-ConfigDedicated-extendedUpPTS,SoundingRS-UL-ConfigDedicatedAperiodic-extendedUpPTS) is configured, theSRS parameters in a new set of RRC parameter may be used for UE totransmit SRS in extended UpPTS resource, otherwise, the legacy SRSparameters (e.g., SoundingRS-UL-ConfigDedicated,SoundingRS-UL-ConfigDedicatedAperiodic) may be used for UE to transmitSRS in legacy SRS resource. In an example, the parameter srs-UpPtsAddmay be separately configured for SRS trigger type 0 and trigger 1. A newksrs table for trigger type 0 and type 1 may be based on whether thecorresponding srs-UpPtsAdd is configured.

In an example embodiment, in an LAA cell, a UE may detect the size of anending DL partial subframe by decoding a common PDCCH DCI on thedownlink subframe. DCI format 1C may indicate ending partial downlinksubframe format. Subframe configuration for LAA may employ 4 bits.Reserved information bits may be added until the size is equal to thatof format 1C used for very compact scheduling of one PDSCH codeword

In an example, if the UE detects common PDCCH DCI referring to subframen in subframes n−1 or n, the UE may assume the number of OFDM symbols insubframe n according to the detected DCI. In an example, if the UE doesnot detect common PDCCH DCI in subframe n and the UE does not detectcommon PDCCH DCI in subframe n−1, the UE is not required to use thesubframe n for updating the CSI measurement. In an example, a field inthe DCI indicates the length of the subframe. Example values of thefield and the corresponding indication is the following. 0: Nextsubframe is 3 OFDM symbols, 1: Next subframe is 6 OFDM symbols, 2: Nextsubframe is 9 OFDM symbols, 3: Next subframe is 10 OFDM symbols, 4: Nextsubframe is 11 OFDM symbols, 5: Next subframe is 12 OFDM symbols, 6:Next subframe is full (14 Symbols), 7: Current subframe is partial 3OFDM symbols, 8: Current subframe is partial 6 OFDM symbols, 9: Currentsubframe is partial 9 OFDM symbols, 10: Current subframe is partial 10OFDM symbols, 11: Current subframe is partial 11 OFDM symbols, 12:Current subframe is partial 12 OFDM symbols, 13: Current subframe isfull (14 Symbols) and end of transmission, 14: Reserved, and 15:Reserved.

In an example, DCI format 1C is used to indicate this LAA commonsignalling. If the end subframe is partial subframe, then the endpartial subframe configuration of a DL transmission burst is indicatedto the UE in the end subframe and the previous subframe. The UE mayexpect that the information signalled in both the above subframes isconsistent. In an example implementation, if the UE receives anindication of an end partial subframe in the current subframe but doesnot receive this signalling in the previous subframe, then the UE is notrequired to further process the subframe. If the end subframe is a fullsubframe, then such signalling may or may not be present. In an exampleDL transmission burst, an end partial subframe may not immediatelyfollow an initial partial subframe.

There is a need to implement a mechanism for a partial beginning uplinksubframe after a partial and/or full ending downlink subframe. CurrentUpPTS mechanism and RRC configuration of variable X can be implementedto configure a partial uplink subframe in an LAA cell. Implementation oflegacy mechanism and using current UpPTS mechanism may reduce uplinkchannel access and/or resource efficiency. The larger the gap period,the higher is the probability that another node (e.g. another LTE and/orWiFi node) obtains channel access before the UE does (this may block theUEs access to channel for uplink transmission). In legacy LTE systems,the variable X for determining UpPTS period is semi-staticallyconfigured employing one or more information element in one or more RRCmessages transmitted by an eNB to the UE. In a legacy special subframe,a UE may not be expected to be configured with 2 additional UpPTSSC-FDMA symbols for special subframe configurations {3, 4, 7, 8} fornormal cyclic prefix in downlink and 4 additional UpPTS SC-FDMA symbolsfor special subframe configurations {1 2, 3, 4, 6, 7, 8} for normalcyclic prefix in downlink.

Adopting legacy formats and configuration employed in legacy specialsubframe may reduce network efficiency and channel access. Some exampleembodiments disclose mechanisms for transition from downlink to uplinktransmission in an LAA cell in a UE.

Subframes may be available for uplink transmission when LAA uplink issupported. In an LAA cell, uplink transmission timing is advanced by NTA(NTA in terms of Ts or equally called TA period) as shown in exampleFIG. 16. A UE advances its transmission timing based on TAC receivedfrom the eNB, e.g. to compensate for round-trip propagation delay. Thismay imply that from a UE transmitter uplink subframe timing starts andends earlier than downlink subframes. A guard period is needed whendownlink transmission ends and uplink transmission starts in a UE. TheeNB may not be able to determine the exact NTA amount, since the UE mayautonomously change the NTA in some scenarios. A guard period may berequired so that uplink and downlink transmission timings do not overlapin a TDD system. In addition, LBT period for a UE may create atransmission gap between downlink transmission and uplink transmission.FIG. 11 shows an example uplink and downlink timings in a UE.

In an example embodiment, the downlink/uplink switching time, guardperiod, and/or LBT may provide a transmission gap. Other UEs/nodes (e.g.Wifi nodes) may acquire the channel after downlink transmission ends,and during the gap. This may not allow a UE to acquire the channel andtransmit uplink signals when the UE is granted an uplink resource aftera downlink burst. In an example, transmission of reservation signals bya UE may enable to reserve the channel and reduce the possibility oflosing a channel A reservation signal may be at least one pre-definedsignal, e.g., reference signal, SRS, RACH, extension of cyclic prefixand/or the like.

In an LAA system, when an eNB transmits a full downlink subframe, thenext available subframe for uplink transmission may be a partial uplinksubframe due to the gap (e.g. depending on DL_UL_switching time, NTArequirements, and/or LBT process). In an LAA system, when an eNBtransmits an end partial downlink subframe, the next available subframefor uplink transmission may be a full or partial uplink subframe due totransmission gap (e.g. including DL_UL_switching time, NTA requirements,and/or LBT process).

Uplink transmissions may start after an ending DL subframe. In anexample, a DL subframe may end at DL symbol s of the DL subframe n.Uplink subframe may start at least afterDL_UL_Interval=TA+DL_UL_Switching+LBT_duration of the end of the ULsymbol s of the corresponding UL subframe n (in terms of uplink subframetiming). In an example, when DL_UL_Interval is 2 symbols, and DLsubframe ends at DL symbol 8 (9 symbol duration) of subframe n, thenuplink transmission may start at earliest in UL symbol 11 and may lastfor 3 symbols in subframe n (assuming normal cyclic prefix and 14symbols in a subframe). In an example, when DL_UL_Interval is 1 symbols,and DL subframe n is a full subframe, then uplink transmission may startat UL symbol 1 and last for 13 symbols in subframe n+1 (assuming normalcyclic prefix). UL symbol timing may be TA in advance of DL symboltiming.

In an example, TA may depend on propagation delay and may range up totens of micro seconds depending on the UE distance to the eNBtransceiver. In an example, DL_UL_switching may depend on transceiverhardware limitations, and may be in range of micro-seconds or less, e.g.DL_UL_switching may be considered zero, then a gap duration (or astarting symbol) may be DL_UL_Interval=TA+LBT_duration. In an example,LBT period may be in the range of tens of micro seconds, for example, 25usec, or one LTE symbol. In an example, a gap duration (or a startingsymbol) may be DL_UL_Interval=TA+25 usec. In an example, a gap duration(or a starting symbol) may be DL_UL_Interval=25 usec, when TA is notconsidered (e.g. TA equal or close to zero). In an example, a gapduration (or a starting symbol) may be DL_UL_Interval=1 symbol. Symbol 0of uplink subframe may be employed for TA, DL_UL_switching and/orLBT_period. In an example, a UE may transmit after downlink transmissionburst without performing LBT if the regulatory rules and UE/eNBimplementation permit such transmission. In an example, a gap duration(or a starting symbol) may be DL_UL_Interval=0. In an example, a UE maybe required to perform LBT for a duration of 25 usec (e.g. LBT cat-2)before starting uplink transmission.

In an example embodiment, a starting symbol of uplink subframe n+1 maybe signalled by a common DCI or dedicated DCI. For example, a basestation may transmit a common DCI on an LAA cell to indicate a startingsymbol and/or time of uplink subframe n+1. For example, a base stationmay transmit dedicated DCI (e.g. uplink grant DCI) via an LAA cell orthe cell scheduling the LAA cell. The dedicated DCI may indicate thestarting symbol and/or time of the PUSCH. A base station may transmit toa wireless device an uplink grant DCI comprising a field indicatinguplink resources for an uplink subframe of the LAA cell, and a fieldindicating a first starting position in a plurality of startingpositions in the uplink subframe. For example, dedicated DCI transmittedon an LAA cell or the cell scheduling the LAA cell may indicate astarting symbol of an uplink subframe. In an example, a field in uplinkgrant DCI may indicate a value indicating a starting symbol and/or time(DL_UL_Interval). The DCI may be transmitted in one or more subframesprior to the subframe including a starting symbol and/or time(DL_UL_Interval). In an example, the dedicated DCI may comprise DCIfield indicating starting symbol and/or time of subframe n+1. The DCIfield may comprise 2 bits indicating one of values e.g. 0, 1, 2, 3indicating one of the four states of starting symbol and/or time(DL_UL_Interval). In an example, DL_UL_Interval may be equal to TA+25usec, DL_UL_Interval may be equal to 1 symbol, DL_UL_Interval may beequal to 25 usec, or DL_UL_Interval may be equal to 0.

FIG. 18 shows a first example for a gap period of 1 symbol and a secondexample for a gap period of TA+25 usec. In an example, a UE may berequired to perform LBT for a duration of one symbol (e.g. LBT cat-4)before starting uplink transmission. Other LBT durations and processesmay be defined for uplink transmission. The wireless device mayconstruct one or more transport blocks employing the dedicated DCI. Thewireless device may transmit the one or more transport blocks in theuplink resources starting from the starting position of the uplinksubframe. In an example embodiment, DL end subframe before the uplinksubframe may be a downlink partial subframe or a downlink full subframe.The size of partial uplink subframe n+1, may be 14 minus a gap period.For example, when the gap period is 1, the size of the partial uplinksubframe may be 13.

In an example, when an ending DL subframe is a downlink partialsubframe, uplink subframe may employ an uplink partial subframeconfiguration (e.g. depending on ending DL partial subframe duration). Agap period may be defined (e.g. in an eNB). The gap period may berequired to provide an interval for at least(DL_UL_switch+TA+LBT_period). The size of ending DL partial subframe maybe downlink burst specific. For example, two downlink bursts transmittedby a cell may have different ending DL partial subframe sizes dependingon when the downlink burst started and/or the MCOT duration in downlink.FIG. 17 shows examples of DL and UL transmission timings in a UE. In anexample, TA may be 5 micro-seconds, LBT period may be 1 symbol or 25micro-seconds, DL_UL_switch may be 3 micro-seconds or less, a gap may betwo symbols. Gap may be larger than or equal to(DL_UL_switch+TA+LBT_period). In an example, no signal may betransmitted in: gap period−(DL_UL_switch+TA+LBT_period). In an example,a reservation signal may be transmitted in this period. Time durationpresented here are for example only, and other durations may beimplemented (e.g. a different gap period, a different LBT period, and/ora different DL_UL_switch etc). In order to have an efficient gap period,gap period may be configured to be equal or larger than(DL_UL_switch+TA+LBT_period). In an example, reservation signals may betransmitted, gap period may be equal or larger than(DL_UL_switch+TA+LBT_period+reservation_signal_period). In an example,when a one symbol LBT is required for uplink signal transmission, thegap period should be greater than one symbol, e.g. 2 or 3 symbols.

In an example embodiment, the duration of partial ending uplink subframemay be burst specific. For example, the duration of partial endinguplink subframe may depend on the duration of the downlink endingsubframe, and/or other configuration parameters. UpPTS period may beemployed for transmission of SRS and/or random access preamble. In anexample, other signals may be transmitted during the UpPTS.

In an example embodiment, a gap period may be pre-specified andpre-determined. Gap period may impose some limitations on TA (and as aresult cell radios), and/or LBT period. Pre-configuring a gap periodmay, for example, limit the cell radius. In an example, LAA cells may beemployed for small cells and may not be expected to operate as largecells. For example, a fixed gap period of one symbol may be defined andimplemented. In an example, a fixed gap period of two symbols may beimplemented. In an example, a gap period of k micro seconds may bedefined, wherein k is predefined, e.g. 50 micro-seconds, etc.

In an example embodiment, a gap period may be configured employing anRRC parameter. Such configuration may provide flexibility in configuringthe gap period (and UpPTS period) in an LAA cell. Different bursts mayemploy the same gap period until RRC configuration parameter changes.For example, an RRC message may comprise configuration parameters of anLAA cell comprising one or more parameters indicating the duration of agap period, e.g. 1 symbol. The gap period (e.g. in terms of a number ofgap symbols) may be indicated to the UE with the RRC parameter with twostates (1 bit), e.g., {1, 2}, or four states (2 bits), e.g. {1, 2, 3,4}. Other examples may be provided. In an example, the parameter may bea common parameter and may be configured the same value for UEscommunicating employing the LAA cell. For example, the gap period may betransmitted in a SIB message. In an example embodiment, the valuesconfigured by RRC may be applicable to some DL partial subframedurations. In an example, multiple allowable gap periods may beconfigured. When a first LBT attempt fails, a UE may perform LBTemploying a second gap period.

In an example embodiment, a gap period may be signalled by a common DCIor dedicated DCI. For example, a common DCI transmitted on an LAA cellor PCell may indicate the size of the gap period. For example, dedicatedDCI transmitted on an LAA cell or the cell scheduling the LAA cell mayindicate the size of the gap period (e.g. in uplink grant DCI). The DCImay be transmitted in the same and/or one or more subframes prior to thesubframe including the gap period. In an example, DCI format 1C may beused, e.g. employing a predefined RNTI (e.g. the same DCI that carriesthe size of the partial ending DL subframe). Such configuration mayprovide flexibility in configuring the gap period (and UpPTS period) inan LAA cell for a given burst. Different bursts may employ different gapperiods depending on the DCI parameter. For example, DCI may compriseone or more parameters indicating the duration of a gap period, e.g. 1symbol. The gap period (e.g. in terms of a number of gap symbols) may beindicated to the UE with DCI field with two states (1 bit), e.g., {1,2}, or four states (2 bits), e.g. {1, 2, 3, 4}. Other examples may beprovided. In an example embodiment, the values transmitted by DCI may beapplicable to some DL partial subframe durations. In an example,multiple allowable gap periods may be configured. When a first LBTattempt fails, a UE may perform LBT employing a second gap period.

In an example embodiment, a value of X may be signalled by a common DCIor dedicated DCI. For example, a common DCI transmitted on an LAA cellor PCell may indicate a value of X. For example, dedicated DCItransmitted on an LAA cell or the cell scheduling the LAA cell mayindicate a value of X (and e.g. using a special subframe configurationin the table above). In an example, a field in uplink grant DCI mayindicate a value indicating X. The DCI may be transmitted in the sameand/or one or more subframes prior to the subframe including the gapperiod. In an example, DCI format 1C may be used, e.g. employing apredefined RNTI (e.g. the same DCI that carries the size of the partialending DL subframe). Such configuration may provide flexibility inconfiguring the gap period (and UpPTS period) in an LAA cell for a givenburst. Different bursts may employ different gap periods (and UpPTSperiods) depending on the DCI parameter. For example, DCI may compriseone or more parameters indicating a value of X, e.g. 1 symbol. A valueof X (e.g. in terms of a number of symbols) may be indicated to the UEwith DCI field with two states (1 bit), e.g., {1, 2}, or four states (2bits), e.g. {1, 2, 3, 4}. Other examples may be provided. In an exampleembodiment, the values transmitted by DCI may be applicable to some DLpartial subframe durations. In an example, multiple allowable X valuesmay be configured. When a first LBT attempt fails, a UE may perform LBTemploying a second X value.

In an example embodiment, a starting symbol of (partial) beginninguplink subframe may be signalled by a common DCI or dedicated DCI. Forexample, a common DCI transmitted on an LAA cell may indicate a startingsymbol of uplink subframe (e.g. UpPTS). For example, dedicated DCItransmitted on an LAA cell or the cell scheduling the LAA cell mayindicate a starting symbol of uplink subframe (e.g. using a specialsubframe configuration). In an example, a field in uplink grant DCI mayindicate a value indicating a starting symbol. The DCI may betransmitted in the same and/or one or more subframes prior to thesubframe including the gap period. In an example, DCI format 1C may beused, e.g. employing a predefined RNTI (e.g. the same DCI that carriesthe size of the partial ending DL subframe). Such configuration mayprovide flexibility in configuring a starting symbol (and gap period,and UpPTS period) in an LAA cell for a given burst. Different bursts mayemploy different gap periods depending on the DCI parameter. Forexample, DCI may comprise one or more parameters indicating a startingsymbol of UpPTS, e.g. symbol 8. A starting symbol of UpPTS (e.g. interms of symbol number) may be indicated to the UE with DCI field withtwo states (1 bit), e.g., {12, 13}, or four states (2 bits), e.g. {7, 9,11, 13}. Other examples may be provided. In an example embodiment, thevalues transmitted by DCI may be applicable to some DL partial subframedurations. In an example, multiple allowable starting symbol of UpPTSmay be configured. When a first LBT attempt fails, a UE may perform LBTemploying a second starting symbol value.

In an example embodiment, when the DL partial subframe is larger than avalue, for example for DL partial subframe size of 11 and/or 12 symbols,no partial uplink subframe may be defined. For example, the last symbolmay be employed for LBT and/or reservation signals, and no uplink data,RACH and/or SRS signals may be transmitted in the subframe and uplinktransmission may start from the next subframe (from beginning of symbol0).

In an example embodiment, a pre-defined signal, for example, SRS, RACH,reference signals, and/or reservation signals may be transmitted duringa partial uplink subframe. For example, SRS may be implemented for thepartial uplink subframe to provide the eNB with uplink channelinformation.

Example embodiments may be implemented for when the last subframe of aDL burst is a full subframe. Transition from a full DL subframe n to anuplink subframe n+1 may be defined. Due the required gap period, thesubsequent uplink subframe n+1 may not be a full subframe. In an exampleembodiment, the size of an uplink subframe (e.g. after a full DLsubframe) may be specified. Legacy TDD special subframe does not definesuch a configuration (a full DL subframe followed by an UL subframe). Inan example, a UE may transmit PUSCH TBs in uplink subframe n+1.

In an example embodiment, a gap period may be specified and determinedfor starting uplink transmission in uplink subframe n+1. Gap period mayimpose some limitations on TA (and as a result cell radios), and/or LBTperiod. Pre-configuring a gap period may, for example, limit the cellradius. In an example, LAA cells may be employed for small cells and maynot be expected to operate as large cells. In such a scenario, symbol 0of uplink subframe may be employed for TA, DL_UL_switching and/or LBTperiod. For example, a fixed gap period of one symbol may be defined andimplemented to determine a starting position in uplink subframe n. In anexample, a gap period of k micro seconds may be defined to determine astarting position in uplink subframe n, wherein k is predefined, e.g. 25usec, 50 usec, etc. In an example, uplink starting position in subframen+1 may be beginning of symbol 0 of subframe n+1, 25 usec from thebeginning of subframe n+1, 25 usec+TA from the beginning of subframen+1, beginning of symbol 1 of subframe n+1. A wireless device mayperform an LBT process before the starting position to determine whetherthe channel is clear for uplink transmission.

In an example, multiple allowable gap periods may be configured todetermine a starting position in an uplink subframe. When a first LBTattempt for a first starting position fails, a UE may perform LBT for asecond starting position (second gap period). For example, a UE mayperform LBT in symbol 0. The UE may be allowed to LBT in symbol 7, whenLBT in symbol 0 fails. Other symbol numbers may be configured in anexample, e.g. symbol 1 and 7.

In an example embodiment, a gap period for an starting position may beconfigured employing an RRC parameter. Such configuration may provideflexibility in configuring the gap period in an LAA cell. Differentbursts may employ the same gap period to determine an starting positionuntil RRC configuration parameter changes. For example, an RRC messagemay comprise configuration parameters of an LAA cell comprising one ormore parameters indicating the duration of a gap period (or startingposition) to determine starting position for uplink transmissions in anuplink subframe, e.g. symbol 1, zero, 25 usec, 25 usec+TA. The gapperiod (e.g. in terms of a number of gap symbols, or in terms ofpredefined starting position values) may be indicated to the UE with theRRC parameter with two states (1 bit), e.g., {1, 2}, or four states (2bits), e.g. {1, 2, 3, 4}. Other examples may be provided. In an example,the parameter may be a common parameter and may be configured the samefor UEs communicating employing the LAA cell. For example, the gapperiod for determining a starting position may be transmitted in a SIBmessage. In an example embodiment, the values configured by RRC may beapplicable to some DL partial subframe durations.

In an example, multiple allowable gap periods or starting positions maybe configured. When a first LBT attempt for a first starting position(first gap period) fails, a UE may perform LBT employing a secondstarting position (second gap period). For example, a UE may perform LBTin symbol 0. The UE may be allowed to LBT in symbol 7, when LBT insymbol 0 fails. Other symbol numbers may be configured in anotherexample, e.g. symbol 1 and 7.

In an example embodiment, a gap period may be signalled by a common DCIor dedicated DCI. For example, a common DCI transmitted on an LAA cellmay indicate the size of the gap period. For example, dedicated DCItransmitted on an LAA cell or the cell scheduling the LAA cell mayindicate the size of the gap period (e.g. in uplink grant DCI). The DCImay be transmitted in the same and/or one or more subframes prior to thesubframe including the gap period. In an example, DCI format 1C may beused, e.g. employing a predefined RNTI (e.g. the same DCI that carriesthe size of the partial ending DL subframe). Such configuration mayprovide flexibility in configuring the gap period (starting position) inan LAA cell for a given burst. Different bursts may employ different gapperiods (starting positions) depending on the DCI parameter. Forexample, DCI may comprise one or more parameters indicating the durationof a gap period (starting position), e.g. beginning of symbol 1, zero,25 usec, 25 usec+TA. The gap period (e.g. in terms of a number of gapsymbols, or in terms of predefined starting position values) may beindicated to the UE with DCI field with two states (1 bit), e.g., {1,2}, or four states (2 bits), e.g. {1, 2, 3, 4}. Other examples may beprovided. In an example embodiment, the values transmitted by DCI may beapplicable to some DL partial subframe durations. In an example,multiple allowable gap periods for multiple starting positions may beconfigured. When a first LBT attempt fails, a UE may perform LBTemploying a second gap period.

In an example embodiment, a starting symbol of subframe n+1 may besignalled by a common DCI or dedicated DCI. For example, a common DCItransmitted on an LAA cell may indicate a starting symbol of subframen+1. For example, dedicated DCI transmitted on an LAA cell or the cellscheduling the LAA cell may indicate the size of the gap period (e.g. inuplink grant DCI). For example, dedicated DCI transmitted on an LAA cellor the cell scheduling the LAA cell may indicate a starting symbol ofuplink subframe. In an example, a field in uplink grant DCI may indicatea value indicating a starting symbol. The DCI may be transmitted in oneor more subframes prior to the subframe including the gap period for thestarting position. In an example, DCI format 1C may be used, e.g.employing a predefined RNTI (e.g. the same DCI that carries the size ofthe ending DL subframe). Such configuration may provide flexibility inconfiguring the gap period for an starting position of an uplinksubframe in an LAA cell for a given burst. Different bursts may employdifferent gap periods depending on the DCI parameter. For example, DCImay comprise one or more parameters indicating a starting position ofsubframe n+1, e.g. beginning of symbol 1, zero, 25 usec, 25 usec+TA. Astarting symbol of subframe n+1 (e.g. in terms of symbol number, and/ora time duration) may be indicated to the UE with DCI field with twostates (1 bit), e.g., {1, 2}, or four states (2 bits), e.g. {0, 1, 2,3}. In an example, multiple allowable starting symbol of subframe n+1may be configured. An eNB may transmit DCI (e.g. uplink grant DCI,common DCI) comprising a plurality of starting position for an uplinksubframe. When a first LBT attempt for a first starting position fails,a UE may perform LBT employing a second gap period for a second startingposition. In an example, an uplink grant for subframe n+1 (single and/ormulti-subframe grant) may include one or more parameters indicating oneor more starting symbol of subframe n+1.

In an example embodiment, one or more gap periods, and/or one or morestarting positions may be configured. For example, when LBT fails in afirst allowable transmission symbol, the UE may perform a subsequent LBTfor transmission on the next allowable transmission starting symbol.

The size of partial uplink subframe n+1, may be 14 minus a gap period.The gap period may determine a starting position for transmission in anuplink subframe. For example, when the gap period is 1, the size of thepartial uplink subframe may be 13. The starting position may be thebeginning of symbol 1 (the second symbol in a subframe).

In an example, gap period may be equal or larger than(DL_UL_switch+TA+LBT_period+reservation_signal_period). One or more ofthese parameters may be zero. For example, when reservation signal isnot transmitted, reservation_signal_period may be considered as zero. Inan example DL_UL_switch may be considered zero. In an example, when noLBT is performed, LBT period may be zero. In another example, LBT maybe, e.g. 25 micro-seconds, one symbol, etc.

The UE may construct one or more transport blocks for transmission inthe uplink subframe. A UE may perform an LBT procedure for transmissionof uplink transport blocks. The UE may transmit the transport blocks inthe uplink subframe employing fields in the uplink grant, e.g. uplinkradio resources (transport block), modulation and coding, RV and/orother transmission format and parameters. The UE may transmit uplinktransport blocks in response to an LBT process being successfullycompleted (indicating a clear channel).

Upon reception of a timing advance command for a TAG containing theprimary cell or PSCell, the UE may adjust uplink transmission timing forPUCCH/PUSCH/SRS of the primary cell or PSCell based on the receivedtiming advance command.

An eNB may transmit to a wireless device DCI comprising an uplink grant(e.g. at least one field indicating an assignment of radio resourceblocks, MCS, RV, and/or the like) and/or a starting position for anuplink subframe. The DCI may comprise one or more fields indicating astart symbol and/or time for LBT procedures and/or uplink transmission.In an example, the DCI may comprise one or more parameters indicatingthat uplink transmission is via a partial subframe. The UE may perform25 us LBT or Cat 4 LBT procedure before the uplink transmission. In anexample, the UE may obtain channel access before the UE starts uplinktransmission. In an example, a UE may have one LBT process opportunityper subframe, when one starting position is indicated by one or moreDCIs and/or one or more RRC messages. In an example, when a UE cannotaccess the channel from a first indicated starting position due to LBTfailure, the UE may drop the whole UL subframe.

Additional starting positions in an uplink subframe may enhance theefficiency of a channel access process. The channel access probabilitymay increase when a number of starting positions and LBT procedures inan uplink subframe increases. For example, an LBT process performed by aUE may not indicate a clear channel for a first starting position (e.g.,symbol 0, 25 usec, TA+25 usec, symbol 1, etc). The UE may perform LBTprocedure for a second starting position and begin UL transmission whena second LBT process indicates a clear channel (e.g., a first symbol ofsecond slot). Performing LBT in multiple UL starting positions mayincrease uplink channel efficiency. To benefit from additional ULstarting points, a UE may start transmitting PUSCH either employing afirst position or a second position of a subframe, depending on where anLBT process indicates a clear channel. In an example, second slotboundary may be employed as additional UL starting position for LBTand/or uplink transmission (e.g. symbol 0, symbol 1, 25 usec, and/orTA+25 usec of the second slot).

In an example, an eNB may transmit an RRC message comprising one or moreparameters to indicate whether a UE can start performing LBT and/ortransmit uplink signals from a second starting position (e.g. secondslot boundary) in addition to a first starting position. In an example,the one or more parameters may indicate a plurality of allowed startingpositions in an uplink subframe corresponding to an uplink grant. In anexample, a UE may start a channel access procedure for UL transmissionfrom a second position (e.g. second slot boundary, second symbolposition) in response to the UE failing to access the channel at a firststarting position. A plurality of starting positions may be configuredfor an uplink subframe.

In an example embodiment, starting positions of UL subframe transmissionmay be dynamically indicated to the UE in an UL grant DCI. In anexample, LBT procedure and uplink transmission starting times may beindicated by DCI (e.g. uplink DCI grant comprising uplink grant foruplink transmission in one or more subframes). A base station maytransmit one or more DCIs comprising at least one uplink grant field(uplink resource block assignment, MCS, RV, etc) and one or more fieldsindicating a plurality of allowed starting positions in an uplinksubframe. In an example, an UL grant may indicate resource allocationwith a starting position in a first or a second slot of a subframe.Depending on whether the UE clears LBT for a first starting position ora second starting position, the UE may employ the first or the secondstarting positions for transmission of one or more transport blocks. Inan example, transmission parameters (MCS, TBS, HARQ ID, NDI, or RV etc.indicated by fields in the DCI) may be the same in both cases.

The eNB may transmit to a wireless device DCI comprising an uplink grantfor UL transmission. In response to the UE LBT not indicating a clearchannel for a first starting position (e.g. at symbol 0, symbol 1, 25usec, or TA+25 usec of a first slot), the UE may start LBT and uplinktransmission for a second starting position (e.g. of a second slot).

In an example, when an LBT process for a first starting position doesnot indicate a clear channel, the UE may perform an LBT for a partialsubframe transmission. The UE may employ rate matching and/or puncturingfor transmission of one or more transport blocks in the uplink.

In an example, multiple starting positions may be configured by one ormore RRC messages and/or one or more DCIs (e.g. uplink DCI grants). TheeNB may transmit one or more DCIs indicating an uplink grant for asubframe. The UE may attempt transmission for a first starting positionof a subframe. When the LBT process for the first starting positionfails, the UE may attempt another LBT for a second starting position ofthe subframe and performs transmission if the second LBT is successful.

According to various embodiments, a device such as, for example, awireless device, off-network wireless device, a base station, and/or thelike, may comprise one or more processors and memory. The memory maystore instructions that, when executed by the one or more processors,cause the device to perform a series of actions. Embodiments of exampleactions are illustrated in the accompanying figures and specification.Features from various embodiments may be combined to create yet furtherembodiments.

FIG. 20 is an example flow diagram as per an aspect of an embodiment ofthe present disclosure. A wireless device may receive one or moremessages at 2010. The Message(s) may comprise configuration parametersof a licensed assisted access (LAA) cell.

Downlink control information (DCI) for the LAA cell may be received at2020. According to an embodiment, the DCI may be dedicated DCI. The DCImay comprise a at least one first field and at least one second field.The at least one first field may indicate uplink resources for an uplinksubframe of the LAA cell, e.g. resource block assignment, transmissionformat, MCS, RV, etc. The at least one second field may indicate a firststarting position (or a gap period) in a plurality of starting positions(or gap periods) in the uplink subframe. The first starting position maybe determined, at least, based on a sum of twenty-five micro-secondsplus a timing advance value. According to an embodiment, the secondfield may comprise two bits of information. According to an embodiment,the plurality of starting positions may comprise: a beginning of symbolzero, a beginning of symbol one, and twenty-five micro-seconds after thebeginning of symbol zero.

One or more transport blocks may be constructed at 2030 employing theDCI. At 2040, one or more transport blocks may be transmitted the in theuplink resources starting from the first starting position.

According to an embodiment, the wireless device may perform alisten-before-talk (LBT) process for the twenty-five micro-seconds.According to an embodiment, the uplink subframe may start earlier than adownlink subframe by the timing advance value. According to anembodiment, the wireless device may not transmit any uplink signals onthe LAA cell during a gap period before the first starting position.According to an embodiment, the wireless device may receive a fulldownlink subframe in a subframe preceding the uplink subframe. Accordingto an embodiment, the wireless device may receive a partial downlinksubframe in a subframe preceding the uplink subframe. According to anembodiment, the wireless device may receive a timing advance commandcomprising the timing advance value, and adjust uplink transmissiontiming for one or more uplink channels based on the timing advancevalue.

The UL transmission timing for PUSCH/SRS of a secondary cell is the sameas the primary cell if the secondary cell and the primary cell belong tothe same TAG. In an example, if the primary cell in a TAG has a framestructure type 1 and a secondary cell in the same TAG has a framestructure type 2, UE may assume that NTA≥624.

If the UE is configured with a SCG, the UL transmission timing forPUSCH/SRS of a secondary cell other than the PSCell may be the same asthe PScell if the secondary cell and the PSCell belong to the same TAG.

In an example implementation, upon reception of a timing advance commandfor a TAG not containing the primary cell or PSCell, if the servingcells in the TAG have the same frame structure type, the UE may adjustuplink transmission timing for PUSCH/SRS of the secondary cells in theTAG based on the received timing advance command where the ULtransmission timing for PUSCH/SRS is the same for the secondary cells inthe TAG.

In an example implementation, upon reception of a timing advance commandfor a TAG not containing the primary cell or PSCell, if a serving cellin the TAG has a different frame structure type compared to the framestructure type of another serving cell in the same TAG, the UE mayadjust uplink transmission timing for PUSCH/SRS of the secondary cellsin the TAG by using NTAoffset=624 regardless of the frame structure typeof the serving cells and based on the received timing advance commandwhere the UL transmission timing for PUSCH/SRS is the same for thesecondary cells in the TAG.

The timing advance command for a TAG may indicate the change of theuplink timing relative to the current uplink timing for the TAG asmultiples of 16 T_(s).

In an example implementation, in case of random access response, an11-bit timing advance command, TA, for a TAG indicates NTA values byindex values of TA=0, 1, 2, . . . , 256 if the UE is configured with aSCG, and TA=0, 1, 2, . . . , 1282 otherwise, where an amount of the timealignment for the TAG is given by NTA=TA×16. In other cases, a 6-bittiming advance command, TA, for a TAG indicates adjustment of thecurrent NTA value, NTA,old, to the new NTA value, NTA,new, by indexvalues of TA=0, 1, 2, . . . , 63, where NTA,new=NTA,old+(TA−31)×16.Here, adjustment of NTA value by a positive or a negative amountindicates advancing or delaying the uplink transmission timing for theTAG by a given amount respectively.

For a timing advance command received on subframe n, the correspondingadjustment of the uplink transmission timing may apply from thebeginning of subframe n+6. For serving cells in the same TAG, when theUE's uplink PUCCH/PUSCH/SRS transmissions in subframe n and subframe n+1are overlapped due to the timing adjustment, the UE may completetransmission of subframe n and not transmit the overlapped part ofsubframe n+1.

If the received downlink timing changes and is not compensated or isonly partly compensated by the uplink timing adjustment without timingadvance command, the UE may changes NTA accordingly.

In an example embodiment, the size of a gap period may result in amaximum allowed NTA value (e.g. in an ending DL subframe in an LAAsystem, and/or in a special subframe of a Licensed-cell). In an exampleembodiment, an eNB may transmit one or more message (e.g. RRC message)configuring a maximum NTA value. In an example, a maximum allowed NTAvalue may be pre-specified. For example, maximum NTA value may be 5, 10,or 15 micro-seconds. Other examples may be provided. UE behaviour whenmaximum NTA value is reached may be defined to enhance uplinkperformance and/or reduce interference. In legacy LTE systems, a processis implemented to trigger certain actions when the uplink transmissiontiming difference between the pTAG and any of the two sTAGs or betweenthe two sTAGs of at least a maximum value, e.g. 32.47 μs. There is nomechanism to limit the value of NTA regarding of the timing differencevalue. Such mechanism may be needed to increase radio link efficiency,e.g. when the cell radius is relatively large. Example embodiments mayimprove downlink/uplink switching and uplink transmission when framestructure 2 and/or 3 is implemented.

In an example implementation, the UE initial transmission timing errormay be less than or equal to ±Te where the timing error limit value Temay depend on a channel bandwidth. This requirement may apply when it isthe first transmission in a DRX cycle for PUCCH, PUSCH and SRS or it isthe PRACH transmission. The reference point for the UE initial transmittiming control requirement may be the downlink timing of the referencecell minus (N_(TA-Ref)+N_(TAoffset))×T_(s). The downlink timing isdefined as the time when the first detected path (in time) of thecorresponding downlink frame is received from the reference cell.NTA_Ref for PRACH is defined as 0. (N_(TA) _(_) _(Ref)+N_(TAoffset)) (inTs units) for other channels is the difference between UE transmissiontiming and the Downlink timing immediately after when the last timingadvance was applied. NTA_Ref for other channels is not changed untilnext timing advance is received.

When it is not the first transmission in a DRX cycle or there is no DRXcycle, and when it is the transmission for PUCCH, PUSCH and SRStransmission, the UE may be capable of changing the transmission timingaccording to the received downlink frame of the reference cell. The UEmay be required to adjust its timing to within ±Te in a TAG when,changing the downlink SCell for deriving the UE transmit timing forcells in the sTAG configured with one or two uplinks; in this TAG thetransmission timing error between the UE and the reference timingexceeds ±Te; and/or configured with a pTAG and one or two sTAG, thetransmission timing difference between TAGs does not exceed the maximumtransmission timing difference (e.g., 32.47 us) after such adjustment.

If the transmission timing difference after such adjustment is biggerthan the maximum transmission timing difference (e.g., 32.47 us) UE maystop adjustment in this TAG. The reference timing may be (N_(TA) _(_)_(Ref)+N_(TAoffset))×T_(s) before the downlink timing of the referencecell.

In an example, if NTA after such adjustment is bigger than the maximumallowed NTA, a UE may stop adjustment in this TAG. In an example, if NTAafter such adjustment is bigger than the maximum allowed NTA, a UE maystop uplink transmission on one or more SCells in this TAG.

In an example embodiment, adjustments made to the UE uplink timing underthe above mentioned scenarios may follow these rules: 1) The maximumamount of the magnitude of the timing change in one adjustment may be Tqseconds. 2) The minimum aggregate adjustment rate may be 7*TS persecond. 3) The maximum aggregate adjustment rate may be Tq per 200 ms.

An eNB may transmit one or more MAC TA commands including a timingadvance value for a TAG. In an example embodiment, a UE may stoptransmitting on one or more SCells if after timing adjusting due to areceived MAC TA command, the NTA exceeds the maximum allowed NTA on acell. Increasing NTA above the limit, may cause issues in a specialsubframe, or in switching from an ending DL subframe in an LAA cell toan UL subframe.

In an example embodiment, if the received downlink timing changes and isnot compensated or is partly compensated by the uplink timing adjustmentwithout timing advance command, the UE may change NTA accordingly (ifNTA does not increase the maximum allowed NTA value). A UE may stoptransmitting on one or more cells if after such timing adjusting, theNTA exceeds the maximum allowed NTA on a cell.

An eNB may transmit one or more MAC TA commands including a timingadvance value for a TAG. In an example embodiment, a UE may not adjustuplink timing to more than maximum allowed NTA if after timing adjustingdue to a received MAC TA command, the NTA exceeds the maximum allowedNTA on a cell. Increasing NTA above the limit, may cause issues in aspecial subframe, or in switching from an ending DL subframe in an LAAcell to an UL subframe.

In an example embodiment, if the received downlink timing changes and isnot compensated or is partly compensated by the uplink timing adjustmentwithout timing advance command, the UE may changes NTA accordingly (ifNTA does not increase the maximum allowed NTA value). In an example, ifthe received downlink timing changes and is not compensated or is partlycompensated by the uplink timing adjustment without timing advancecommand, the UE may not change NTA when NTA exceeds the maximum allowedNTA value.

In an example embodiment, when NTA exceeds the maximum allowed NTA valuea UE may trigger certain actions at PHY, MAC, and/or RRC layer. Forexample, a UE may not increase NTA (autonomously or due to receipt of aMAC CE) beyond the maximum allowed NTA value. For example, a UE may stoptransmission of uplink signals on one or more cells in a TAG when NTAincreases (autonomously or due to receipt of a MAC CE) beyond themaximum allowed NTA value. In an example, a UE may transmit a MAC or RRCmessage to the eNB indicating the issue and/or a cause for the issue.For example, the UE may transmit an RRC comprising a parameterindicating that NTA exceeded the maximum allowed value. In animplementation, the eNB may deactivate one or more SCells to resolve theissue. In an implementation, the eNB may transmit one or more messageschanging a maximum NTA value for one or more cells. For example, an RRCmessage may reconfigure the cell with different X values, gap values,and/or special subframe configuration.

In this specification, “a” and “an” and similar phrases are to beinterpreted as “at least one” and “one or more.” In this specification,the term “may” is to be interpreted as “may, for example.” In otherwords, the term “may” is indicative that the phrase following the term“may” is an example of one of a multitude of suitable possibilities thatmay, or may not, be employed to one or more of the various embodiments.If A and B are sets and every element of A is also an element of B, A iscalled a subset of B. In this specification, only non-empty sets andsubsets are considered. For example, possible subsets of B={cell1,cell2} are: {cell1}, {cell2}, and {cell1, cell2}.

In this specification, parameters (Information elements: IEs) maycomprise one or more objects, and each of those objects may comprise oneor more other objects. For example, if parameter (IE) N comprisesparameter (IE) M, and parameter (IE) M comprises parameter (IE) K, andparameter (IE) K comprises parameter (information element) J, then, forexample, N comprises K, and N comprises J. In an example embodiment,when one or more messages comprise a plurality of parameters, it impliesthat a parameter in the plurality of parameters is in at least one ofthe one or more messages, but does not have to be in each of the one ormore messages.

Many of the elements described in the disclosed embodiments may beimplemented as modules. A module is defined here as an isolatableelement that performs a defined function and has a defined interface toother elements. The modules described in this disclosure may beimplemented in hardware, software in combination with hardware,firmware, wetware (i.e hardware with a biological element) or acombination thereof, all of which are behaviorally equivalent. Forexample, modules may be implemented as a software routine written in acomputer language configured to be executed by a hardware machine (suchas C, C++, Fortran, Java, Basic, Matlab or the like) or amodeling/simulation program such as Simulink, Stateflow, GNU Octave, orLabVIEWMathScript. Additionally, it may be possible to implement modulesusing physical hardware that incorporates discrete or programmableanalog, digital and/or quantum hardware. Examples of programmablehardware comprise: computers, microcontrollers, microprocessors,application-specific integrated circuits (ASICs); field programmablegate arrays (FPGAs); and complex programmable logic devices (CPLDs).Computers, microcontrollers and microprocessors are programmed usinglanguages such as assembly, C, C++ or the like. FPGAs, ASICs and CPLDsare often programmed using hardware description languages (HDL) such asVHSIC hardware description language (VHDL) or Verilog that configureconnections between internal hardware modules with lesser functionalityon a programmable device. Finally, it needs to be emphasized that theabove mentioned technologies are often used in combination to achievethe result of a functional module.

The disclosure of this patent document incorporates material which issubject to copyright protection. The copyright owner has no objection tothe facsimile reproduction by anyone of the patent document or thepatent disclosure, as it appears in the Patent and Trademark Officepatent file or records, for the limited purposes required by law, butotherwise reserves all copyright rights whatsoever.

While various embodiments have been described above, it should beunderstood that they have been presented by way of example, and notlimitation. It will be apparent to persons skilled in the relevantart(s) that various changes in form and detail can be made thereinwithout departing from the spirit and scope. In fact, after reading theabove description, it will be apparent to one skilled in the relevantart(s) how to implement alternative embodiments. Thus, the presentembodiments should not be limited by any of the above describedexemplary embodiments. In particular, it should be noted that, forexample purposes, the above explanation has focused on the example(s)using LAA communication systems. However, one skilled in the art willrecognize that embodiments of the disclosure may also be implemented ina system comprising one or more TDD cells (e.g. frame structure 2 and/orframe structure 1). The disclosed methods and systems may be implementedin wireless or wireline systems. The features of various embodimentspresented in this disclosure may be combined. One or many features(method or system) of one embodiment may be implemented in otherembodiments. Only a limited number of example combinations are shown toindicate to one skilled in the art the possibility of features that maybe combined in various embodiments to create enhanced transmission andreception systems and methods.

In addition, it should be understood that any figures which highlightthe functionality and advantages, are presented for example purposesonly. The disclosed architecture is sufficiently flexible andconfigurable, such that it may be utilized in ways other than thatshown. For example, the actions listed in any flowchart may bere-ordered or only optionally used in some embodiments.

Further, the purpose of the Abstract of the Disclosure is to enable theU.S. Patent and Trademark Office and the public generally, andespecially the scientists, engineers and practitioners in the art whoare not familiar with patent or legal terms or phraseology, to determinequickly from a cursory inspection the nature and essence of thetechnical disclosure of the application. The Abstract of the Disclosureis not intended to be limiting as to the scope in any way.

Finally, it is the applicant's intent that only claims that include theexpress language “means for” or “step for” be interpreted under 35U.S.C. 112. Claims that do not expressly include the phrase “means for”or “step for” are not to be interpreted under 35 U.S.C. 112.

What is claimed is:
 1. A method comprising: receiving, by a wireless device, one or more messages comprising configuration parameters of a licensed assisted access (LAA) cell; receiving downlink control information (DCI) for the LAA cell, wherein the DCI comprises: a first field indicating uplink resources for an uplink subframe of the LAA cell; and a second field indicating that a starting position of the uplink subframe is based on a sum of a listen-before-talk (LBT) period and a timing advance value; generating one or more transport blocks based on the DCI; and transmitting, using the uplink resources and starting from the starting position of the uplink subframe, the one or more transport blocks.
 2. The method of claim 1, wherein the second field indicates a value of a plurality of values associated with determining the starting position of the uplink subframe.
 3. The method of claim 2, wherein the plurality of values comprises: a first value associated with a beginning of symbol zero of the uplink subframe; a second value associated with twenty-five micro-seconds after the beginning of symbol zero of the uplink subframe; a third value associated with a number of microseconds after the beginning of symbol zero of the uplink subframe, wherein the number of microseconds is based on twenty-five micro-seconds plus a timing advance; and a fourth value associated with a beginning of symbol one of the uplink subframe.
 4. The method of claim 1, wherein the LBT period is twenty-five micro-seconds.
 5. The method of claim 1, further comprising determining the starting position of the uplink subframe, wherein the timing advance value is associated with uplink transmission by the wireless device.
 6. The method of claim 1, wherein the second field comprises two bits of information.
 7. The method of claim 1, further comprising, performing, by the wireless device, an LBT process for the LBT period.
 8. The method of claim 1, wherein the uplink subframe starts earlier than a downlink subframe by the timing advance value.
 9. The method of claim 1, wherein the wireless device is configured to not transmit uplink signals on the LAA cell during a gap period before the starting position.
 10. The method of claim 1, further comprising receiving, by the wireless device, a full downlink subframe in a subframe preceding the uplink subframe.
 11. The method of claim 1, further comprising receiving, by the wireless device, a partial downlink subframe in a subframe preceding the uplink subframe.
 12. The method of claim 1, wherein the DCI is dedicated DCI.
 13. The method of claim 1, further comprising: receiving, by the wireless device, a timing advance command comprising the timing advance value; and adjusting uplink transmission timing for one or more uplink channels based on the timing advance value.
 14. A wireless device comprising: one or more processors; and memory storing instructions that, when executed by the one or more processors, cause the wireless device to: receive one or more messages comprising configuration parameters of a licensed assisted access (LAA) cell; receive downlink control information (DCI) for the LAA cell, wherein the DCI comprises: a first field indicating uplink resources for an uplink subframe of the LAA cell; and a second field indicating that a starting position of the uplink subframe is based on a sum of a listen-before-talk (LBT) period and a timing advance value; generate one or more transport blocks based on the DCI; and transmit, using the uplink resources and starting from the starting position of the uplink subframe, the one or more transport blocks.
 15. The wireless device of claim 14, wherein the second field indicates a value of a plurality of values associated with determining the starting position of the uplink subframe.
 16. The wireless device of claim 15, wherein the plurality of values comprises: a first value associated with a beginning of symbol zero of the uplink subframe; a second value associated with twenty-five micro-seconds after the beginning of symbol zero of the uplink subframe; a third value associated with twenty-five micro-seconds plus at least one microsecond after the beginning of symbol zero of the uplink subframe; and a fourth value associated with a beginning of symbol one of the uplink subframe.
 17. The wireless device of claim 14, wherein the LBT period is twenty-five micro-seconds.
 18. The wireless device of claim 14, wherein the instructions, when executed by the one or more processors, further cause the wireless device to determine the starting position of the uplink subframe, wherein the timing advance value is associated with uplink transmission by the wireless device.
 19. The wireless device of claim 14, wherein the second field comprises two bits of information.
 20. The wireless device of claim 14, wherein the instructions, when executed by the one or more processors, further cause the wireless device to perform an LBT process for the LBT period.
 21. The wireless device of claim 14, wherein the uplink subframe starts earlier than a downlink subframe by the timing advance value.
 22. The wireless device of claim 14, wherein the instructions, when executed by the one or more processors, further cause the wireless device to not transmit uplink signals on the LAA cell during a gap period before the starting position.
 23. The wireless device of claim 14, wherein the instructions, when executed by the one or more processors, further cause the wireless device to receive a full downlink subframe in a subframe preceding the uplink subframe.
 24. The wireless device of claim 14, wherein the instructions, when executed by the one or more processors, further cause the wireless device to receive a partial downlink subframe in a subframe preceding the uplink subframe.
 25. The wireless device of claim 14, wherein the DCI is dedicated DCI.
 26. The wireless device of claim 14, wherein the instructions, when executed by the one or more processors, further cause the wireless device to: receive a timing advance command comprising the timing advance value; and adjust uplink transmission timing for one or more uplink channels based on the timing advance value.
 27. A system comprising: a base station comprising: one or more processors; and memory storing first instructions that, when executed by the one or more processors of the base station, cause the base station to: transmit one or more messages comprising configuration parameters of a licensed assisted access (LAA) cell; and transmit downlink control information (DCI) for the LAA cell, wherein the DCI comprises: a first field indicating uplink resources for an uplink subframe of the LAA cell; and a second field indicating that a starting position of the uplink subframe is based on a sum of a listen-before-talk (LBT) period and a timing advance value; and a wireless device comprising: one or more processors; and memory storing second instructions that, when executed by the one or more processors of the wireless device, cause the wireless device to: generate one or more transport blocks based on the DCI; and transmit, using the uplink resources and starting from the starting position of the uplink subframe, the one or more transport blocks.
 28. The system of claim 27, wherein the second field indicates a value of a plurality of values associated with determining the starting position of the uplink subframe.
 29. The system of claim 28, wherein the plurality of values comprises: a first value associated with a beginning of symbol zero of the uplink subframe; a second value associated with twenty-five micro-seconds after the beginning of symbol zero of the uplink subframe; a third value associated with twenty-five micro-seconds plus at least one microsecond after the beginning of symbol zero of the uplink subframe; and a fourth value associated with a beginning of symbol one of the uplink subframe.
 30. The system of claim 27, wherein the LBT period is twenty-five micro-seconds.
 31. The system of claim 27, wherein the second instructions, when executed by the one or more processors of the wireless device, further cause the wireless device to determine the starting position of the uplink subframe, wherein the timing advance value is associated with uplink transmission by the wireless device.
 32. The system of claim 27, wherein the second field comprises two bits of information.
 33. The system of claim 27, wherein the second instructions, when executed by the one or more processors of the wireless device, further cause the wireless device to perform an LBT process for the LBT period.
 34. The system of claim 27, wherein the uplink subframe starts an amount of time earlier than a downlink subframe, wherein the amount of time corresponds to the timing advance value.
 35. The system of claim 27, wherein the second instructions, when executed by the one or more processors, further cause the wireless device to not transmit uplink signals on the LAA cell during a gap period before the starting position.
 36. The system of claim 27, wherein the second instructions, when executed by the one or more processors of the wireless device, further cause the wireless device to receive a full downlink subframe in a subframe preceding the uplink subframe.
 37. The system of claim 27, wherein the second instructions, when executed by the one or more processors of the wireless device, further cause the wireless device to receive a partial downlink subframe in a subframe preceding the uplink subframe.
 38. The system of claim 27, wherein the DCI is dedicated DCI.
 39. The system of claim 27, wherein the second instructions, when executed by the one or more processors of the wireless device, further cause the wireless device to: receive a timing advance command comprising the timing advance value; and adjust uplink transmission timing for one or more uplink channels based on the timing advance value. 